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TO  THE 

LIBRARY  OF  THE 
MEDICAL  DEPARTMENT 

OF  THE 
UNIVERSITY  OF  CALIFORNIA 


Lea's  Series 
of  Pocket  Text-Books. 


Diseases  of  the  Eye,  Ear 
Nose  and  Throat. 

By  W.  L.  BALLENGER,  M.D,  Lecturer 
on  Rhinology  and  Laryngology,  and 
A.  G.  WIPPERN,  M.D.,  Clinical  Instruc- 
tor in  Diseases  of  the  Nose  and  Throat, 
College  of  Physicians  and  Surgeons, 
Chicago. 

Anatomy. 

By  FREDERICK  J.  BROCKWAY,  M.D., 
Assistant  Demonstrator  of  Anatomy, 
College  of  Physicians  and  Surgeons, 
New  York. 

Bacteriology  and  Hygiene. 

By  W.  E.  COAXES,  JR.,  M.D.,  Instruc- 
tor in  Bacteriology  and  Pathology, 
College  of  Physicians  and  Surgeons, 
Chicago. 

Diagnosis. 

By  C.  P.  COLLINS,  M.  D.,  Attending 
Physician  to  St.  Luke's  Hospital,  New 
York. 

Physiology. 

By  H.  D.  COLLINS,  M.  D.,  Assistant 
Demonstrator  of  Anatomy,  and  W.  H. 
ROCKWELL,  JR.,  A.  B  ,  M.  D.,  Assistant 
Demonstrator  of  Anatomy,  College  of 
Physicians  and  Surgeons,  New  York. 


Gynecology. 

By  MONTGOMERY  A.  CROCKETT, 
A.  B.,  M.  D.,  Adjunct  Professor  of  Ob- 
stetrics and  Clinical  Gynecology,  Med- 
ical Department  .University  ofBuffalo, 
New  York. 

Obstetrics. 

By  DAVID  J.  EVANS,  M.  D.,  Demon- 
strator of  Obstetrics,  McGill  Univer- 
sity, Faculty  of  Medicine,  Montreal. 

Surgery. 

By  BERN  B.  GALLAUDET.M.D.,  Dem- 
onstrator of  Anatomy,  and  Clinical 
Lecturer  on  Surgery,  College  of  Physi- 
cians and  Surgeons,  New  York. 


Dermatology. 

By  JOSEPH  GRINDON,  M.  D.,  Pro- 
fessor of  Dermatology,  St.  Louis  and 
Missouri  Medical  College,  St.  Louis. 

Genito-Urinary  and  Venereal 
Diseases. 

By  SYLVAN  H.  LIKES,  M.D.,  Demon- 
strator of  Pathology  and  Genito-Uri- 
nary Surgery  at  the  College  of  Physi- 
cians and  Surgeons,  Baltimore. 

Chemistry  and  Physics. 

By  WALTON  MARTIN,  M.  D.,  Assist- 
ant Demonstrator  of  Anatomy,  and 
WILLIAM  H.  ROCKWELL,  JR.,  A.  B., 
M.  D.,  Assistant  Demonstrator  of 
Anatomy,  College  of  Physicians  and 
Surgeons,  New  York. 

Practice  of  Medicine. 

By  George  E).  MALSBARY,  M.  D., 
Assistant  to  the  Chair  of  Theory  and 
Practice  of  Medicine,  Medical  College 
of  Ohio,  Cincinnati. 

Histology  and  Pathology. 

By  JOHN  B.  NICHOLS,  M.  D.,  Assist- 
ant in  Pathology,  Medical  Depart- 
ment, University  of  Georgetown,  and 
F.  P.  VALE,  M.  D.,  Demonstrator  of 
Normal  Histology,  Medical  Depart- 
ment, Columbian  University,  Wash- 
ington, D.  C. 

Nervous  and  Mental  Diseases. 

By  CHARLES  S.  POTTS,  M.  D.,  In- 
structor in  Fylectrp- Therapeutics  and 
Nervous  Diseases  in  the  University  of 
Pennsylvania,  Philadelphia. 

Materia  Medica. 

By  WILLIAM  SCHLEIF,  Ph.G.,M.D., 
Instructor  in  Pharmacy  in  the  Uni- 
versity of  Pennsylvania,  Philadelphia. 
Cloth,  $1.50,  net. 

Diseases  of  Children. 

By  GEORGE  M.  TUTTLE,  M.D.,  At- 
tending Physician  to  St.  Luke's  Hos- 
?ital,   Martha  Parsons'   Hospital   for 
hildren    and     Bethesda    Foundling 
Asylum,  St.   Louis,   Mo. 


or ' 


's  Series  of  Pocket  lta&?Bobl(8. 

HISTOLOGY  AND 


R 


A  MANUAL  FOR  STUDENTS  AND  PRACTITIONERS. 


BY 

JOHN  BENJAMIN   NICHOLS,  M.D., 

Demonstrator  of  Histology,  Medical  Department  Columbian  University, 
Washington,  D.  C., 

AND 

FRANK   PALMER  VALE,  M.  D., 

Assistant  in  Pathology,  Medical  Department  University  of  Georgetown, 
Washington,  D.  C. 


SERIES   EDITED  BY 

BERN    B.   GALLAUDET,   M.D., 

Demonstrator  of  Anatomy  and  Instructor  in  Surgery,  College  of  Physicians  and  Surgeons, 
Columbia  University,  New  York;  Visiting  Surgeon,  Bellevue  Hospital,  New  York. 

ILLUSTRATED  WITH  TWO  HUNDRED  AND  THIRTEEN   ENGRAVINGS. 


LEA   BROTHERS  &  CO., 
PHILADELPHIA    AND    NEW    YORK. 


^J 


Entered  according  to  Act  of  Congress,  in  the  year  1899,  by 

LEA  BROTHERS  &  CO., 
In  the  Office  of  the  Librarian  of  Congress,  at  Washington.    All  rights  reserved. 


PREFACE. 


IT  is  the  purpose  of  this  work  to  present  all  the  essential 
facts  relating  to  the  normal  histology  and  the  pathological 
anatomy  and  histology  of  man  in  a  systematic  and  concise 
way.  In  subjects  so  well  established  as  these,  originality 
of  data  is  little  to  be  expected,  and  the  chief  object  to  be 
aimed  at  is  arrangement  and  treatment  of  the  subject  in  a 
manner  convenient  and  clear  to  students  and  practitioners 
of  medicine,  for  whom  this  treatise  is  intended.  It  is 
attempted  to  present  the  subject  up  to  the  most  recent  dis- 
coveries and  developments,  avoiding  points  unsettled  and  in 
doubt. 

The  part  on  normal  histology  is  written  entirely  by  Dr. 
Nichols,  that  on  pathology  entirely  by  Dr.  Yale.  Each  is 
fully  responsible  for  the  statements  in  his  own  part,  and  for 
those  only. 

J.  B.  NICHOLS. 
FKANK  P.  VALE. 
WASHINGTON,  D.  C. 


180257 


CONTENTS. 


NORMAL   HISTOLOGY. 


CHAPTER    I. 

PAGE 

INTRODUCTION 17 

CHAPTER    II. 

CELLS  AND  EXTRA-CELLULAR  ELEMENTS 22 

CHAPTER  III. 
REPRODUCTION  AND  DEVELOPMENT 33 

CHAPTER  IV. 
THE  TISSUES 42 

CHAPTER  V. 
GLANDS  ;  Mucous  AND  SEROUS  MEMBRANES  ;  ORGANS 67 

CHAPTER  VI. 
THE  CIRCULATORY  SYSTEM 75 

CHAPTER  VII. 

THE  LYMPHATIC  SYSTEM 82 

CHAPTER  VIII. 
BLOOD  AND  LYMPH 91 

CHAPTER  IX. 

BLOOD-GLANDS  AND  DUCTLESS  GLANDS 104 

5 


6  CONTENTS. 

CHAPTEE  X. 

PAGE 

THE  ALIMENTARY  SYSTEM Ill 

CHAPTEK  XL 
THE  RESPIRATORY  SYSTEM 141 

CHAPTER  XII. 
THE  SKIN 151 

CHAPTER  XIII. 
THE  URINARY  ORGANS 158 

CHAPTER  XIV. 
THE  REPRODUCTIVE  SYSTEM 172 

CHAPTER   XV. 
MUSCULAR  AND  SKELETAL  STRUCTURES 198 

CHAPTER  XVI. 
THE  NERVOUS  SYSTEM  202 


PATHOLOGY. 


INTRODUCTORY ...'.. 243 


GENERAL    PATHOLOGY. 

CHAPTER   I. 
PATHOLOGY  OF  THE  BLOOD  AND  CIRCULATION 247 

CHAPTER  II. 
PATHOLOGY  OP  NUTRITION  274 


CONTENTS.  7 

SPECIAL    PATHOLOGY. 
CHAPTEK  III. 

PAGE 

DISEASES  OF  THE  BLOOD 309 

CHAPTER  IV. 
DISEASES  OF  THE  CIRCULATORY  SYSTEM  .   .   .   .   .    .  ...   .   .   .    .    318 

CHAPTEK  V. 
DISEASES  OF  THE  RESPIRATORY  ORGANS    .  .  .  ,,.  .,  : 332 

CHAPTER  VI. 
DISEASES  OF  THE  GASTRO-JNTESTINAL  TRACT 359 

CHAPTER   VII. 

DISEASES  OF  THE  URINARY  ORGANS 403 

CHAPTER  VIII. 

DISEASES  OF  THE  NERVOUS  SYSTEM     ....  .    420 


NORMAL    HISTOLOGY. 


NORMAL  HISTOLOGY. 


CHAPTER    I. 
INTRODUCTION. 

Histology  (from  the  Greek  f<jroc,  tissue,  and  ^0/07,  discourse) 
is  a  branch  of  anatomy  treating  of  the  minute  or  microscopi- 
cal structure  of  living  organisms.  In  its  full  significance  it 
relates  to  the  entire  organic  kingdom,  all  plants  and  animals 
alike.  Within  large  classes  of  animals  or  plants  the  structure 
of  the  tissues  is  quite  uniform  ;  but  on  comparing  one  large 
group  of  organic  types  with  another,  differences  in  the  structure 
appear,  although  there  are  a  fundamental  unity  and  similarity 
throughout. 

The  histologic  structure  of  man,  with  which  the  present 
treatise  deals,  is  substantially  the  same  as  that  of  all  the  mam- 
malia, the  points  of  variation  being  few  and  slight;  hence 
human  histology  and  mammalian  histology  are  almost  identi- 
cal. In  passing  to  the  classes  of  birds  and  reptiles,  however, 
marked  differences  begin  to  appear,  as  in  the  forms  of  the  red 
blood-corpuscles,  while  the  general  structure  remains  similar. 

Analysis  of  histologic  structures  :  In  analyzing  the  organism 
into  its  anatomic  and  histologic  elements  we  find  that  they 
are  arranged  in  an  ascending  series  of  aggregations.  The 
ultimate  elements  of  all  are  the  atoms  and  molecules  ;  as  the 
scope  of  histologic  science  does  not  extend  beyond  the  limits 
of  microscopic  vision,  the  atomic  and  molecular  structure  of 
tissues  and  cells  does  not  come  within  its  field,  but  is  covered 
by  organic  chemistry  and  physics,  with  different  methods  of 
investigation. 

The  smallest  elements  with  which  histology  deals  are  masses: 

19 


20  INTRODUCTION. 

hence  chemistry  and  physics  cover  the  atomic  and  molecular 
structure ;  histology,  the  minute  molar  structure  of  organisms. 

The  ultimate  and  smallest  perceptible  histologic  elements 
of  distinct  individual  character  may  be  divided  into  two 
classes,  cells  and  non-cellular  or  extracellular  elements.  By 
the  union  of  these  elements  tissues  are  formed,  as  fibrous  tis- 
sue, muscular  tissue ;  by  the  union  of  tissues  organs  are 
formed ;  a  combination  of  organs  all  working  together  for 
the  accomplishment  of  some  general  function  constitutes  a 
system  or  tract,  as  the  reproductive  system,  the  alimentary 
tract;  while  all  the  systems  together  make  up  the  complete 
organism. 

The  ascending  grades  of  aggregation  in  organic  structure 
are,  then,  after  atoms  and  molecules,  cells  and  extracellular 
elements,  tissues,  organs,  systems,  the  organism. 

The  subject  will  here  be  elaborated  in  the  order  correspond- 
ing to  this  analysis,  beginning  with  the  fundamental  elements, 
cells,  etc.,  then  taking  up  their  aggregations  in  tissues,  and 
finally  studying  the  structure  of  the  organs  making  up  the 
various  systems  of  organic  activity. 

Histologic  technique  :  The  histologic  examination  of  tissues 
is  carried  out  entirely  by  microscopic  methods.  To  gain  an 
adequate  idea  of  histology,  actual  examination  of  the  tissues 
under  the  microscope  is  necessary.  The  use  of  the  microscope 
and  the  preparation  of  specimens  of  tissues  for  microscopic 
examination  involve  numerous  delicate  procedures,  the  mastery 
of  which  requires  much  special  study  and  experience.  Objects 
cannot  be  examined  in  bulk  under  the  microscope,  but  require 
special  treatment  before  their  structure  can  be  made  visible. 
For  one  thing  they  have  to  be  very  thin,  so  thin  as  to  be 
transparent;  hence,  solid  tissues  have  to  be  cut  into  thin 
slices,  or  sections,  about  yj-^th  millimetre  thick.  In  their 
natural  state  most  tissues  are  colorless,  so  that  the  details  of 
the  structure  cannot  well  be  made  out.  To  make  the  details 
more  visible  it  is  customary  to  stain  the  sections  with  certain 
dyes,  of  which  a  considerable  number  are  available  for  vari- 
ous purposes.  Some  stains  have  an  affinity  for  some  parts  of 
the  tissues,  other  stains  for  other  parts ;  thus  by  the  employ- 
ment of  various  materials  and  methods  different  structures  can 
be  brought  plainly  into  view  and  differentiated.  The  nuclear 


HJSTOLOGIC  TECHNIQUE.  21 

dyes,  for  instance,  such  as  hsematoxylin,  carmine,  methylene- 
blue,  constitute  a  class  of  stains  very  much  used,  which 
impart  to  the  cell-nuclei  a  deep  color,  while  they  leave  the 
bodies  of  the  cells  uncolored ;  the  general  stains,  as  eosin,  on 
the  contrary,  stain  the  cell-protoplasm,  but  not  the  nuclei. 
There  are  numerous  other  processes  to  be  carried  out ;  but  the 
limits  of  this  work  do  not  permit  the  consideration  of  practi- 
cal methods,  for  which  reference  may  be  made  to  the  numer- 
ous special  works  on  that  subject. 


CHAPTER    II. 
CELLS  AND   EXTRACELLULAR  ELEMENTS. 

Elements  of  tissues  :  The  ultimate  elements  of  which  tissues 
are  composed  are  cells  and  extracellular  (or  intercellular)  sub- 
stances. Of  these  the  cells  comprise  by  far  the  bulk  of  the 
tissues  and  play  the  chief  part  in  the  phenomena  of  life.  The 
body  protoplasm,  which  is  the  seat  and  source  of  all  vital 
phenomena,  is  located  in  the  cells. 

The  non-cellular  elements,  produced  by  the  vital  activities 
of  the  cells,  provide  a  connection,  support,  and  framework  for 
the  cells,  which,  composed  as  they  are  of  semifluid  protoplasm, 
have  little  consistency  of  their  own  and  are  scarcely  capable 
of  self-support.  The  cells  are  alive  and  the  seat  of  life ;  the 
function  of  the  extracellular  elements  is  merely  mechanical, 
and  they  do  not  possess  any  real  vitality  of  their  own. 

The  cell :  A  cell  is  the  smallest  perceptible  organization  of 
protoplasm  having  a  definite  and  complete  individuality,  struct- 
ure, and  vitality  of  its  own.  It  manifests  in  miniature  all 
the  characteristics  of  life  exhibited  by  the  entire  organism. 
It  is  a  unit  of  organic  structure  and  organic  activity.  It  is 
the  source  and  the  seat  of  vital  manifestations. 

The  name  "cell"  literally  means  a  small  inclosed  space. 
This  meaning  does  not  express  a  correct  conception  of  the 
nature  of  cells.  The  term  arose  from  the  fact  that  vegetable 
cells,  with  their  prominent  walls  and  their  transparent  though 
vital  contents,  appear  like  a  mass  of  cavities  separated  by 
partitions.  The  term  "corpuscle,"  often  used  synonymously 
with  cell,  better  expresses  the  idea. 

Classes  of  cells:  All  cells  have  a  fundamental  similarity  in 
origin,  structure,  and  nature ;  but  as  they  actually  occur  they 
vary  much  in  form  and  function  in  different  situations.  Two 
classes,  in  general,  can  be  distinguished  : 

1 .  Generalized  or  undijferentiated,  independent,  free-living 
22 


STRUCTURE  OF  CELLS.  23 

cells,  each  endowed  with  all  the  attributes  of  vitality  and 
capable  of  complete  existence  singly  and  by  itself.  They  are 
typical  cells.  Of  this  kind  are  (a)  the  single  cells  of  which 
some  of  the  lowest  (unicellular)  forms  of  living  beings  con- 
sist, as  the  bacteria,  desmids,  and  diatoms  among  plants ;  and 
the  protozoa — amrebse,  foraminifera,  infusoria — among  animals ; 
(6)  the  ova  and  spores  from  which  all  the  higher  organisms 
develop,  each  being  an  independent  and  undifferentiated  cell, 
and  derived  from  the  union  of  two  other  free  though  not  typi- 
cal cells,  the  female  ovule  and  the  male  sperm-cell ;  (c)  cer- 
tain actively  vital  cells  living  free  in  the  fluids  and  tissues  of 
the  highest  organisms,  exemplified  by  the  white  blood-corpuscle, 
or  leukocyte. 

2.  Differentiated  or  specialized  cells.  In  unicellular  animals 
and  plants  the  single  cell  carries  on  all  the  operations  of  life. 
In  the  forms  that  through  evolution  have  become  more  highly 
developed,  instead  of  a  single  cell  the  organism  is  composed 
of  many  cells ;  and  instead  of  each  cell  in  the  multicellular 
organism  carrying  on  all  the  functions  of  life,  those  operations 
are  divided  among  different  sets  of  cells,  some  serving  one 
purpose,  some  another.  This  is  differentiation,  or  specializa- 
tion ;  it  is  a  true  division  or  organization  of  labor,  and  by  it  a 
maximum  result  is  accomplished  with  the  minimum  and  most 
economical  expenditure  of  energy.  In  such  a  differentiated 
organism  the  cells  in  various  situations  and  devoted  to  various 
purposes  vary  accordingly  in  form,  structure,  and  function. 
Each  great  class  of  plant  and  animal  forms  has  its  own  char- 
acteristic types  of  cells. 

The  specialized  fixed  cells  of  mammalian  tissues  may  be  in 
general  divided  into  four  classes  :  epithelial  cells,  connective- 
tissue  cells,  nerve-cells,  and  muscle-cells. 

It  is  worthy  of  note  that  the  young  or  embryonal  forms  of 
cells  that  are  specialized  when  mature  often  partake  of  the 
more  generalized  character,  thus  exemplifying  the  principle 
that  the  different  phases  through  which  an  organism  passes 
in  the  course  of  its  genesis  and  development  are  indicative 
of  the  different  forms  through  which  its  species  passed  in  the 
course  of  its  evolution. 

Structure  of  cells :  All  cells  have  a  body  of  protoplasm, 
which  in  most  cases  contains  a  nucleus  (Fig.  1).  The  centra- 


24 


CELLS  AND  EXTRACELLULAR   ELEMENTS. 


FIG.  1. 


Diagrammatic  representation  of  an  am- 
reboid  cell,  showing  the  nucleus,  nu- 
clear reticulum,  nucleolus,  the  cen- 
trosome  and  attraction-sphere,  the 
spongioplasm,  hyaloplasm,  and  pseu- 
dopodia. 


some  is  an  important  feature  of  most  cells.  Many  cells  are 
surrounded  by  a  cell-wall,  while  some  have  processes  and  other 
special  features. 

The  cell-body,  or  cytosome :  As  a  general  thing,  the  body  or 

main  (non-nuclear)  portion  of 
cells  is  composed  of  typical 
and  active  protoplasm.  The 
protoplasm  of  cell-bodies  is 
often  called  cytoplasm.  In  typ- 
ical cells,  like  the  leukocyte, 
two  parts  can  be  distinguished 
in  the  protoplasm  :  the  hyalo- 
plasm, a  clear,  semifluid,  motile 
portion  similar  in  appearance 
to  the  white  of  an  egg ;  and  the 
granuloplasm,  or  spongioplasm., 
which  in  the  living  cell  presents 
a  granular  appearance,  but  is 
supposed  by  many  to  be  made 
up  of  fibres  or  a  sponge-like 
reticulum.  The  granular  portion  usually  occupies  the  central 
portion  of  the  cell,  when  it  is  called  the  endoplasm,  or  endo- 
sarc ;  the  hyaline  portion  then  forms  the  outer  part  of  the 
cell,  and  is  called  the  ectoplasm,  or  ectosarc. 

Sometimes  the  protoplasm  contains  granules,  as  of  pigment, 
or  foreign  particles  which  have  been  taken  into  the  soft  sub- 
stance of  the  cell  from  without,  as  bacteria  and  other  bodies 
absorbed  by  leukocytes,  or  food- particles  taken  in  by  the 
small  unicellular  organisms.  Some  cells  contain  vacuoles, 
minute  rounded  cavities  or  spaces ;  in  some  of  the  protozoa 
these  are  contractile,  being  alternately  distended  with  fluid 
and  then  emptied  by  the  contraction  of  the  surrounding  pro- 
toplasm, thus  accomplishing  some  sort  of  circulatory  process; 
certain  human  cells  are  vacuolated.  Cells  often  contain  sub- 
stances elaborated  by  their  own  activity  and  stored  up  in 
their  bodies  in  granules  or  small  masses.  One  of  the  com- 
monest of  these  is  fat ;  cells,  as  in  the  liver,  secreting  mam- 
mary gland,  the  vitelhis  of  the  ovum,  often  contain  small 
fatty  globules.  In  some  cases,  as  in  adipose  tissue,  this  proc- 
ess is  carried  to  an  extreme  degree  and  the  cell  becomes  com- 


CELL-GRANULES.  25 

pletely  filled  and  distended  with  a  solid  mass  of  fat,  the 
original  protoplasm  remaining  only  as  a  thin  atrophied  shell. 
In  plant-cells  the  body  of  the  cell  is  largely  occupied  by  sap, 
starch-granules,  and  the  like.  In  some  cases  the  protoplasm 
becomes  transformed,  so  that  little  vitality  is  left  to  the  cell ; 
as  in  the  horny  layer  of  the  skin,  in  which  the  cells  have  been 
converted  into  a  tough  horny  substance  well  adapted  to  pur- 
poses of  protection. 

Cell-granules :  The  granules  which  occur  in  the  bodies  of 
many  cells  are  of  various  kinds.  Some  are  particles  of  pig- 
ment produced  by  the  action  of  the  cell  or  absorbed  from 
without.  Some  are  produced  artificially  by  the  reagents  em- 
ployed in  the  preparation  of  the  specimen,  not  occurring  in 
the  natural  state ;  even  water  will  cause  the  appearance  of 
granules  in  some  cells.  Other  granules,  which  are  colorless, 
appear  to  be  specializations  of  the  body-protoplasm.  Among 
such  granules  important  distinctions  are  made  out,  especially 
by  their  behavior  with  staining-reagents ;  these  distinctions 
are  especially  serviceable  in  the  study  of  leukocytes.  Some 
granules  will  become  stained  by  one  kind  of  dye,  others  by 
another  kind,  these  staining-peculiarities  corresponding  to  dif- 
ferences in  the  chemical  constitution  of  the  granules. 

Stains  in  which  the  coloring-agent  is  the  acid  part  of  the 
compound,  as  eosin,  are  called  acid  stains  ;  those  in  which  the 
basic  portion  of  the  dyestuff  is  the  staining-principle,  as 
methylene-blne,  are  called  basic  stains;  while  stains  composed 
of  a  mixture  of  acid  and  basic  dyes  are  called  neutral  stains. 

Granules  which  are  colored  by  neutral  stains  are  called 
"  neutrophile  "  ;  those  that  take  basic  stains  are  called  "  baso- 
phile  "  ;  those  that  take  acid  stains  are  best  called  "  oxyphile  " 
f  oc'JC,  acid,  and  ydeco,  to  love),  though  they  are  most  com- 
monly called  "eosinophile  "  (eosin  being  one  of  the  most  potent 
acid  stains),  also  sometimes  "  acidophile  "  (a  barbarous  term). 

Ehrlich's  much-quoted  division  of  the  granules  of  leuko- 
cytes and  other  cells  into  five  classes  is  as  follows:  ^.-granules, 
coarse  oxyphilic  or  eosinophilic  granules,  found  in  certain 
human  leukocytes;  /2-granules,  amphophilic  granules  (taking 
both  acid  and  basic  stains),  occurring  in  the  blood  of  some 
animals  ;  y-granules,  coarse  basophilic  granules,  found  in  mast- 
cells  ;  ^-granules,  fine  basophilic  granules,  at  times  found  in 


26  CELLS  AND  EXTRACELLULAR  ELEMENTS. 

human  leukocytes ;  and  e-granules,  fine  neutrophilic  granules 
(by  some  considered  oxyphilic),  very  common  in  human  leu- 
kocytes. 

The  nucleus :  Most  cells  contain  in  their  interior  a  nucleus, 
a  rounded  structure  distinctly  marked  off  from  the  cell-body. 
It  appears  especially  prominent  when  stained  by  nuclear  and 
basic  dyes,  which  impart  to  the  nucleus  a  deep  color,  while 
the  body  of  the  cell  is  colored  little  or  not  at  all.  Nuclei  are 
inclosed  and  separated  from  the  rest  of  the  cell  by  a  mem- 
brane, the  nuclear  membrane.  The  nucleus  consists  of  two 
portions:  the  nuclear  fibrils,  or  reticulum,  a  network  of  fibers; 
and  the  nuclear  matrix,  a  semifluid  substance  in  the  meshes 
of  the  reticulum. 

The  fibrillar  substance,  again,  is  composed  of  two  parts,  a 
homogeneous  ground-substance  called  linin,  supported  in 
which  are  granules,  fibres,  and  filaments  of  a  substance  called 
chromatin.  In  stained  specimens  the  deep  color  shown  by  the 
nucleus  is  taken  by  the  chromatin  (whence  the  name),  while 
the  ground-substance,  or  limn,  and  the  nuclear  matrix  are  less 
colored. 

From  the  phenomena  of  karyokine&is,  the  chromatin  is  sup- 
posed to  be  of  the  highest  significance  and  importance  in  vital 
phenomena,  especially  in  connection  with  reproduction  and 
heredity.  Chromatin  has  been  conjectured  to  be  identical 
with  nuclein,  a  chemical  constituent  of  cells  which  is  regarded 
from  physiological  and  chemical  considerations  as  playing  a 
highly  important  part  in  the  economy  of  cell-activity. 

In  many  cases,  as  in  ova  and  nerve-cells,  the  nucleus  con- 
tains a  little  nucleus  of  its  own,  or  more  than  one,  called  the 
nucleolns.  Most  cells  are  uninucleated,  or  contain  but  a  single 
nucleus  each  ;  certain  classes  of  cells,  however,  arc  multinu- 
cleated,  containing  several  or  numerous  nuclei  each,  as  the 
voluntary  muscle-cells,  osteoclasts,  and  the  giant  cells  present 
in  certain  pathological  processes. 

In  shape,  the  nuclei  are  usually  spheroidal,  oval,  or  discoid  ; 
but  in  different  cases  the  shape  varies  greatly,  and  may  be  ex- 
ceedingly irregular. 

The  location  of  the  nuclei  in  the  cells  varies,  being  some- 
times in  (he  centre,  sometimes  excentric,  sometimes  at  the  very 
periphery  of  the  cell. 


CILIA   AND   FLAG  ELL  A.  27 

Their  size,  in  proportion  to  that  of  the  entire  cell,  also 
varies;  usually  the  nucleus  comprises  but  a  small  part  of  the 
corpuscle  ;  but  in  some  cases,  as  in  the  mononuclear  leukocyte, 
the  nucleus  occupies  the  largest  part  of  the  cell. 

Most  animal  and  vegetable  cells  are  nucleated.  Nuclei 
have  not  been  demonstrated  in  some  of  the  unicellular  organ- 
isms, however,  though  they  are  probably  present.  Among 
mammalian  cells  one  important  class,  the  red  blood- corpuscles, 
is  not  nucleated.  The  nucleus  seems  such  an  essential  feat- 
ure in  the  life  and  reproduction  of  cells  that  cells,  like  the  red 
blood-corpuscles,  that  are  not  nucleated  are  probably  lacking 
in  the  full  attributes  of  vitality. 

The  precise  function  of  the  nucleus  is  not  clear ;  but  it  is 
evidently  of  high  importance,  especially  in  connection  with 
reproduction  and  heredity.  It  is  probably  the  most  vital 
part  of  the  cell,  the  body  largely  serving  nutritive  and  me- 
chanical purposes. 

The  centrosome,  or  polar  corpuscle,  is  a  minute  round  re- 
fractive body  or  point,  situated  in  the  interior  of  the  cell. 
The  protoplasmic  granules  around  it  are  arranged  in  delicate 
radiating  lines,  forming  the  attraction-sphere.  In  resting  or 
non-dividing  cells  it  may  be  within  the  nucleus,  or  just  out- 
side ;  but  in  this  stage  it  is  not  conspicuous  and  is  usually  in- 
visible. During  the  process  of  karyokinetic  cell-division  it 
appears  prominently  in  the  protoplasm  of  the  cell-body,  and 
it  plays  an  important  part  in  this  process,  apparently  exercis- 
ing some  sort  of  polar,  or  directive,  or  attractive  influence  in 
the  division. 

The  cell-wall,  or  cytolemma  :  Many  cells  are  surrounded  with 
a  covering  or  wall,  which  gives  support  and  protection  to  the 
soft  protoplasm.  This  may  be  a  distinct  membrane,  or  a  con- 
densation and  hardening  of  the  outermost  layer  of  protoplasm. 
Some  of  the  lower  unicellular  organisms  secrete  around  them- 
selves a  silicious  or  calcareous  covering.  The  cell-walls  of 
plants  consist  of  cellulose,  a  firm  substance  belonging  to  the 
starch  group,  to  which  the  hardness  of  wood  is  due.  Some 
cells,  as  the  leukocytes,  appear  to  be  devoid  of  a  distinct  cell- 
wall. 

Cilia  and  flagella  :  Certain  kinds  of  cells  have  fine,  hair-like 
processes  or  filaments  projecting  from  their  surface,  capable 


28  CELLS  AND  EXTRACELLULAR   ELEMENTS. 

of  active  vibratory  or  undulatory  movements.  They  are 
composed  of  protoplasm  like  that  of  the  cell-body,  and  their 
motility  is  of  the  same  nature  as  that  of  protoplasm  generally. 
When  they  are  comparatively  short  and  thickly  crowded  on 
the  surface,  or  a  part  of  the  surface,  of  the  cell,  they  are  called 
cilia;  when  they  are  long  and  occur  singly  or  only  in  small 
numbers  on  the  cell,  they  are  called  flagella.  They  occur  not 
only  on  low  organisms,  like  bacteria  and  infusoria,  but  are  of 
wide  distribution  and  great  importance  in  the  human  body; 
e.  <?.,  where  cilia  occur  extensively  on  ciliated  epithelium,  and 
flagella  on  the  spermatozoa. 

The  motion  of  cilia  is  vibratory,  and,  as  they  act  in  unison, 
a  wave-like  motion  results,  which,  acting  from  a  fixed  surface, 
as  in  mammalia,  carries  particles  along  the  surface  or  creates 
currents  in  the  fluids  adjacent. 

The  motion  of  flagella  is  undulatory,  and  when  attached  to 
free  cells  this  movement  rapidly  propels  the  cells  through  the 
fluid  in  which  they  occur,  acting  in  the  same  manner  as  the 
tail  of  a  tadpole  or  fish.  Flagella  therefore  are  a  means  for 
rapid  locomotion  of  spermatozoa,  monads,  and  other  free- 
swimming  cells  provided  with  them. 

Other  cell- processes :  Besides  motile  processes  like  those  just 
described,  some  cells  possess  permanent  and  non-motile  pro- 
jections, which  may  be  very  various  in  form  and  size,  coarse 
or  fine,  long  or  short,  branching  or  very  irregular.  Good  ex- 
amples are  furnished  by  nerve-cells,  bone-cells,  connective- 
tissue  cells. 

Forms  of  cells :  Cells  vary  widely  in  shape,  according  to 
the  situation  in  which  they  occur  and  the  purposes  they  serve. 
The  typical  shape  is  perhaps  spheroidal  or  oval.  The  leuko- 
cytes, which  are  typical  active  cells,  are  spherical  when  at 
rest.  Many  cells  which  when  mature  are  of  diverse  shapes 
are  spheroidal  when  young.  In  a  differentiated  multicellular 
organism  there  is  a  great  diversity  of  form  in  different  locali- 
ties. On  exposed  surfaces  they  become  flattened  or  disk- 
shaped  ;  in  other  situations  they  are  spheroidal,  or  columnar, 
or  elongated,  or  branching,  sheath-like,  or  tubular,  or  alto- 
gether irregular.  But  however  diverse  their  form,  their 
fundamental  type  is  identical  throughout ;  they  are  all  definite 
protoplasmic  bodies,  usually  nucleated. 


VITAL  PROPERTIES  AND  FUNCTIONS  OF  CELLS.      29 

Size  of  cells :  The  size  of  cells  varies  much.  Some  of  the 
bacteria  are  only  about  1  micrornillimetre l  in  diameter ;  these 
are  very  small  cells.  The  diameter  of  ordinary  vegetable 
cells  ranges  from  20  to  100  //;  while  some  plant-cells  are 
fairly  visible  to  the  naked  eye,  nearly  1  mm.  in  diameter. 
The  mammalian  ovum  is  a  very  large  cell,  about  0.2  mm. 
(200  //)  in  diameter.  Human  red  blood-corpuscles  are  about 
7  or  8  IJL  in  diameter,  and  leukocytes  7  to  15  //.  Human  vol- 
untary muscle-cells  range  from  10  to  40  fj.  in  diameter,  and  2 
to  4  cm.  in  length.  The  ordinary  cells  of  human  tissues 
range  from  about  5  to  40  fj.  in  diameter. 

Vital  properties  and  functions  of  cells :  The  study  of  func- 
tion pertains  especially  to  the  science  of  physiology ;  in  his- 
tology it  is,  however,  necessary  to  pay  some  regard  to  func- 
tions, since  function  and  structure  are  intimately  related,  and 
a  consideration  of  the  former  throws  light  on  the  latter,  as  a 
full  understanding  of  the  latter  is  essential  to  an  adequate 
understanding  of  the  former.  The  function  expresses  the 
meaning  of  the  structure. 

The  properties  and  manifestations  of  life  and  organisms  in 
general  reside  in  the  individual  cells.  The  functions  and  ac- 
tivities of  cells  are  the  same  as  those  of  life  itself.  These 
activities  are  usually  divided  into  three  classes,  nutrition,  sensi- 
bility, and  motion. 

Nutrition  broadly  comprehends  the  ingestion  of  food-ma- 
terial ;  its  elaboration  and  assimilation  into  the  organic  struct- 
ure ;  the  rejection  of  waste ;  the  formation  of  the  structural 
organization ;  the  preserving  of  it  intact ;  development  to 
maturity  ;  reproduction ;  decline ;  the  passage  through  a 
definite  life-cycle. 

Independent  free-living  cells,  as  the  unicellular  organisms, 
leukocytes,  etc.,  carry  on  all  these  vital  operations  alone — 
nourish  themselves  through  their  life-cycle,  manifest  irri- 
tability, and  possess  the  power  of  quasi-spontaneous  move- 
ment. The  specialized  cells  of  differentiated  organisms  each 
devote  their  respective  energies  to  some  particular  part  of  the 
work  of  life,  instead  of  each  performing  all  the  vital  functions. 

xThe  linear  unit  employed  in  microscopic  measurements  is  the  micro- 
millimetre,  or  micron,  briefly  designated  by  the  Greek  letter  /*;  it  is  J^QQ  th 
of  a  millimetre,  or  about  2  sibo  tn  of  an 


30  CELLS  AND  EXTRACELLULAR  ELEMENTS. 

Thus  the  functions  of  such  cells  become  distributed  and  dif- 
ferentiated: one  set  of  cells,  in  the  muscular  system,  exercises 
the  power  of  contractility ;  others,  in  the  nervous  system,  are 
specially  arranged  as  seats  of  sensibility  and  consciousness ; 
other  cells  have  chemical  functions,  in  the  secretory  appara- 
tus ;  some  build  up  the  framework  of  the  body,  some  serve  as 
a  covering  to  the  surface,  others  provide  for  reproduction. 

Movements  of  cells  :  The  chief  visible  vital  movements,  of 
automatic  or  quasi-spontaneous  character,  of  which  cells  are 
capable  are:  1,  amoeboid  movement;  2,  contraction;  3,  cili- 
ary movement ;  4,  cyclosis,  or  internal  circulation.  These  are 
all  probably  varying  manifestations  of  one  fundamental  mode 
of  motion.  Besides  these,  a  purely  physical,  not  vital,  micro- 
scopic motion  is  sometimes  observed  in  cells,  namely,  5, 
Brown ian  movement. 

Amoeboid  movement :  Many  free  cells,  as  the  leukocytes  in 
the  blood  and  some  of  the  protozoa,  possess  the  power  of 
spontaneously  protruding  and  withdrawing  processes  of  the 
body-protoplasm.  These  processes  are  called  pseudopod ia  ; 
and  this  kind  of  movement  is  called  amoeboid,  from  the  fact 
that  it  is  characteristic  of  the  protozoon  known  as  the  amoeba. 
At  rest,  the  cells  capable  of  amoeboid  movement  are  usually 
spheroidal ;  but  when  in  motion  their  shape  may  become  very 
irregular. 

The  pseudopodia  have  no  definite  forms  or  size,  but  are  very 
variable  and  irregular.  They  may  be  broad,  or  they  may  be 
slender  and  filamentary  ;  they  are  always  temporary  and  capa- 
ble of  retraction,  unlike  permanent  cell-processes.  By  means 
of  them  the  cells  are  enabled  to  seize  food-particles,  or  to 
move  themselves  about,  extending  a  pseudopodium  in  one 
direction,  and  then  by  enlarging  it  the  body  gradually  follows. 

The  hyaloplasm,  or  clear  outer  part  of  the  protoplasm,  is 
the  more  actively  concerned  in  the  amoeboid  movements  ;  it  is 
the  first  to  be  protruded  in  the  pseudopodia,  while  the  granu- 
lar portion  of  the  protoplasm  more  slowly  follows.  The 
throwing  out  of  the  pseudopodia  is  said  to  be  due  to  currents 
of  the  fluid  protoplasm,  which,  impinging  on  the  periphery 
of  the  cell,  unbounded  by  a  stiff  wall,  cause  it  to  bulge  and 
protrude  at  that  point. 

Contraction  is  a  mode  of  movement,  closely  allied  to  amce- 


INTIMATE  STRUCTURE  OF  CELLS.  31 

bold  movement,  which  is  manifested  by  many  cells.  The 
protoplasm  surrounding  contractile  vacuoles  exhibits  it.  It  is 
especially  the  function  of  muscle-cells,  which  decrease  in 
length  and  at  the  same  time  increase  in  thickness.  This 
movement  is  also  said  to  be  accomplished  by  the  flowing  of 
the  fluid  protoplasm. 

Ciliary  movement :  The  vibratory  movement  of  cilia  and  the 
undulatory  movements  of  flagella  have  been  already  described. 
It  is  a  vital  protoplasmic  movement. 

Cyclosis :  In  certain  vegetable  cells  currents  of  liquid  and 
minute  particles  are  observable  coursing  about  in  definite 
channels  entirely  within  the  cell.  This  movement  is  called 
cyclosis,  or  internal  cell-circulation,  and  is  perhaps  due  to 
spaces  and  channels  in  the  cell-substance,  along  which  the  con- 
tained fluid  is  forced  by  contractions  of  the  protoplasm. 

Brownian  movement:  Fine  microscopic  particles  of  solid 
matter,  if  mixed  with  water  or  certain  slightly  viscid  fluids, 
exhibit  under  the  microscope  a  characteristic  constant  dancing 
or  oscillating  movement.  This  was  first  described  in  1826, 
by  Robert  Brown,  from  whom  it  has  been  called  the  Brownian 
movement ;  it  is  also  called  pedesis.  Its  cause  is  not  under- 
stood. It  is  a  purely  physical  phenomenon,  not  vital ;  but 
granules  within  cells  sometimes  exhibit  this  movement. 

Intimate  structure  of  cells :  The  description  of  cells  above 
given  covers  the  features  observable  by  means  of  the  micro- 
scope. When  we  contemplate  how  from  a  single  microscopic 
cell,  the  ovum,  a  large  organism  can  develop,  composed  of 
millions  of  cells  of  a  highly  differentiated  and  vastly  compli- 
cated structure ;  and  how  ova  indistinguishable  from  one 
another,  though  belonging  to  different  species,  produce  their 
own  kind  with  unerring  fidelity  :  we  are  forced  to  conclude  that 
the  germ-cells  must  contain  elements  or  mechanisms  corre- 
sponding to  and  capable  of  developing  all  the  various  parts  of 
the  full  grown  organism — that  is,  that  they  have  a  vastly  com- 
plex structure  that  is  hidden  from  us  beyond  the  limits  of  micro- 
scopic vision,  and  that  what  we  see  are  but  the  coarsest  feat- 
ures of  their  construction.  Structural  elements  not  ordinarily 
visible  become  manifest  during  karvokinesis.  Between  the 
atomic  and  molecular  structure  of  which  we  gain  some  idea 
through  chemical  science,  and  the  elements  visible  to  us, 


32  CELLS  AND  EXTRACELLULAR  ELEMENTS. 

there  is  in  cells  a  large  field  of  structural  factors  that  is  beyond 
our  powers  of  observation.  If  we  could  penetrate  within  this 
invisible  field,  we  might  find  much  of  histologic  and  structural 
organization  that  would  be  of  the  greatest  interest  and  im- 
portance in  explaining  the  mysteries  of  vital  phenomena. 
But  we  cannot  as  yet  penetrate  it,  and  the  various  vital  struct- 
ures and  units  which  eminent  biologists  have  assumed  as 
entering  into  the  structure  of  cells,  such  as  the  hypothetical 
pangenes,  plasomes,  plastidules,  biophors,  determinants,  and 
the  like,  have  at  present  little  more  than  a  speculative  value. 

Extracellular  elements:  The  non-cellular,  intercellular,  or 
extracellular  constituents  of  tissues  serve  to  connect,  support, 
and  provide  a  mechanical  framework  for  the  cells,  which  of 
themselves  do  not  possess  the  firmness  requisite  for  a  large 
organism.  These  elements  are  not  the  seat  of  any  real  vitality, 
which  pertains  exclusively  to  the  cells ;  they  are  produced  by 
the  vital  activities  of  the  latter. 

The  intercellular  substances  exhibit  considerable  variety, 
and  in  different  tissues  occur  in  varying  proportions  to  the 
total  amount  of  the  cells. 

The  simplest  form  is  the  intercellular  cement,  a  scanty  sub- 
stance which  cements  cells  together.  The  plasma  of  the  blood 
and  the  serum  of  lymph  may  be  regarded  as  a  fluid  intercel- 
lular substance  in  which  the  cells  are  suspended. 

The  greatest  variety  and  quantity  of  extracellular  elements 
occur  in  the  connective  tissues,  where  the  fibres,  the  hyaline 
matrix  of  cartilage,  and  the  mineral  matter  deposited  in  bones 
are  of  this  character. 


CHAPTER    III. 


REPRODUCTION  AND  DEVELOPMENT. 

Origin  of  cells :  Every  cell  is  produced  by  a  preexisting  cell 
— omnis  ceUula  e  celhila.  A  generation  ago  it  was  supposed 
that  under  certain  circumstances  some  of  the  lower  organisms, 
as  the  bacteria,  could  develop  directly  out  of  non-living  mat- 
ter. The  generation  of  life  de  novo  in  such  a  manner  was 
called  abiogenesis,  or  spontaneous  generation.  The  incorrect- 
ness of  that  supposition  has  been  shown,  and  it  is  now  uni- 
versally believed  that  abiogenesis  never  occurs.  Under  all 
circumstances  life  is  always  produced  by  preexisting  life — 
omne  vivurn  e  vivo;  all  protoplasm  is  elaborated  by  preexisting 
protoplasm. 

Modes  of  reproduction  of  cells :  There  are  several  modes  in 
which  cells  reproduce  themselves,  namely  :  1,  direct  division  ; 
2,  budding,  or  gemmation ;  3,  segmentation ;  4,  indirect  di- 
vision, or  karyokinesis. 

FIG.  2. 


Direct  cell-division  (Flemming). 

Direct  division :  In  this  mode  of  cell-division  a  constriction 
appears  in  the  nucleus  and  in  the  cell-body  ;  this  constriction 
gradually  deepens,  until  the  two  parts  become  completely 

3— Hist.  33 


34  REPRODUCTION  AND  DEVELOPMENT. 

separated,  and  the  one  parent-cell  has  become  two  daughter- 
cells.  This  process  is  called  direct  or  amitotic  division  or 
fission  (Fig.  2).  This  method  of  division  sometimes  occurs 
with  some  cells,  but  it  is  believed  to  be  far  less  common  than 
the  indirect  or  karyokinetic  method. 

Budding,  or  gemination:  Occasionally  this  mode  of  cell- 
reproduction  occurs  among  the  protozoa.  A  small  protrusion 
of  protoplasm  appears  at  the  margin  of  the  cell,  gradually 
enlarges,  and  is  finally  separated  from  the  parent  and  becomes 
independent. 

Segmentation :  This  consists  in  the  simultaneous  breaking 
up  of  the  parent-cell  into  a  number  of  small  rounded  cells, 
which  separate,  and  in  their  turn  develop  to  maturity.  It 
occurs  among  some  protozoa,  and  in  human  medicine  is  easily 
observed  in  the  parasite  of  malaria,  which  at  the  end  of  its 
life-period  rather  abruptly  breaks  up  into  from  eight  to  twenty 
minute  hyaline  spheres. 

Indirect  division,  karyokinesis,  or  mitosis,  is  the  usual  and 
chief  mode  by  which  all  cells  reproduce  themselves.  The 
process  is  accomplished  by  a  series  of  definite  changes,  affect- 
ing especially  the  chromatin-filaments  and  centrosomes  (Figs. 
3-8.)  The  stages  of  typical  karyokinesis  may  for  purposes 
of  description  be  capitulated  as  follows : 

1.  Resting  stage. 

2.  Continuous  convolution/  ">  c!ose  s,ke.in' 

{  6,  open  skein. 

3.  Segmented  convolution. 

4.  Equatorial  or  aster  stage. 

5.  Division  of  chromosomes  and  metakinesis. 

6.  Diaster  stage. 

7.  Double  segmented  convolution. 

8.  Double  continuous  convolution. 

9.  Division  of  cell-body. 
10.   Resting  stage. 

In  the  intervals  between  karyokinetic  division,  or  the  rest- 
ing stagef  the  chromatin  of  the  nucleus  is  arranged  in  gran- 
ules, filaments,  or  a  network,  but  not  in  any  definite  manner. 

The  mitotic  process  begins  with  an  enlargement  of  the 
nucleus  and  an  increase  of  the  chromatin  ;  at  the  same  time 
the  centrosome  appears  in  the  body- protoplasm  and  enlarges. 


KAR  YOKINESIS. 
FIG.  3.  FIG.  4. 


35 


Continuous  convolution. 
FIG.  5. 


Metakinesis,  earlier  stage. 


FIG.  7. 


Equatorial  or  aster  stage. 
FIG.  6. 


Metakinesis,  later  stage. 
FIG.  8. 


Diaster  stage.  Double  segmented  convolution. 

Diagrammatic  representation  of  stages  of  karyokinesis  (Flemming). 


36  REPRODUCTION  AND   DEVELOPMENT. 

The  chromatin  develops  into  an  apparently  continuous  and 
single  long  filament  in  a  tangled  skein,  or  dense  convolution,  or 
"  spirem."  This  is  the  stage  of  the  continuous  convolution.  At 
first  the  chromatin-filament  is  fine,  and  is  arranged  in  close, 
crowded  turns  ;  this  formation  is  called  the  close  skein.  Later, 
the  filament  becomes  coarser,  and  the  loops  and  windings  of 
the  convolution  more  open,  forming  the  open  skein.  The 
nuclear  membrane  and  nucleoli  become  gradually  transformed 
into  the  chromatin-filament  and  absorbed  into  the  skein,  and 
thus  disappear,  so  that  no  wall  now  separates  the  nucleus  from 
the  cell-body. 

The  chromatin-filament,  which  heretofore  has  apparently 
been  one  continuous  thread,  then  breaks  up  into  segments, 
forming  the  segmented  convolution.  Each  of  these  segments  is 
called  a  chromosome.  The  chromosomes  form  V-shaped  or 
U-shaped  loops,  and  tend  to  arrange  themselves  with  the 

FIG.  9. 


Cell  (ovum  of  ascaris  megalocephalus)  undergoing  karyokinetic  division  (Kostanecki 
and  Siedlecki).    a,  centrosome  ;  b,  chromosomes. 

angles  toward  a  common  centre  and  the  arms  radiating  out- 
ward. The  number  of  chromosomes  in  different  species  is 
usually  from  four  to  thirty-six  in  each  cell ;  one  crustacean, 
artemia,  has  168.  Human  cells  contain  about  sixteen  chromo- 
somes each.  The  number  of  chromosomes  is  uniform  in  all 
the  cells  of  the  same  species.  In  the  meantime,  during  the 


INDIRECT  DIVISION.  37 

segmentation  of  the  spirem,  the  centrosome  has  divided  into 
two,  which  have  separated  and  become  located  at  opposite 
points  or  poles,  one  on  each  side  of  the  nucleus. 

In  the  equatorial  or  aster  stage  the  process  is  at  its  height. 
The  achromatic  spindle  has  developed,  consisting  of  delicate 
striae,  uncolored  by  the  stain  (whence  the  term  achromatic), 
which  are  arranged  in  the  form  of  two  cones  having  their 
apices  in  the  two  centrosomes,  and  their  bases  directed  toward 
each  other ;  or,  in  other  words,  the  achromatin-fibres  form  a 
fusiform  spindle,  with  the  extremities  in  the  centrosomes  or 
poles  (Fig.  9).  The  chromosomes  become  arranged  in  the 
equatorial  plane  of  this  spindle — that  is,  in  the  plane  bisect- 
ing at  right  angles  the  axis  or  line  connecting  the  two  poles ; 
their  loops  are  directed  inward  toward  the  common  centre; 
their  arms  and  free  extremities  extend  outward  in  a  radiating 
manner,  presenting  the  appearance,  from  the  side,  of  a  star, 
or  aster. 

The  next  stage  is  the  division  of  the  chromosomes  and  migra- 
tion of  their  segments,  or  metakinesis.  The  chromosome-fila- 
ments split  in  two  longitudinally,  beginning  at  the  apex  or 
bend,  and  the  apices  of  the  separated  halves  then  travel  along 
the  threads  of  the  achromatic  spindle  toward  the  two  cen- 
trosomes. 

Thus  the  double  aster  or  diaster  stage  develops.  Around 
each  centrosome  the  daughter-chromosomes  become  arranged 
in  radiating  or  the  aster  form.  The  chromatin  of  the  single 
original  nucleus  has  been  divided  into  two  equal  parts,  to 
form  two  new  da  lighter- nuclei ;  and  it  is  to  be  observed  that 
the  number  of  chromosomes  in  the  daughter-cells  is  precisely 
the  same  as  in  the  parent-cell,  and  remains  constant  through- 
out for  each  species. 

The  free  ends  of  the  chromosome-fibers  become  connected 
by  achromatic  filaments,  and  the  chromatin-fibers  now  undergo 
a  change  precisely  the  reverse  of  that  of  developing  karyo- 
kinesis.  The  double  segmented  convolution,  or  disconnected 
chromosomes,  is  succeeded  by  the  double  continuous  convolu- 
tion: first  the  open  skein  appearing,  then  the  close  skein. 
The  nuclear  membrane  and  nucleoli  appear,  and  ultimately 
the  nuclei  resume  the  condition  of  the  resting  stage.  Simul- 
taneous with  these  retrograde  processes  in  the  nuclei,  division 


38  REPRODUCTION  AND  DEVELOPMENT. 

of  the  cell-body  occurs ;  the  body  has  become  indented,  a  line 
of  cleavage  has  appeared  across  it,  and  it  divides  entirely  into 
two  parts.  Thus  the  original  cell  has  divided  into  two  cells, 
each  like  the  parent  in  all  respects. 

Conjugation :  In  contrast  to  the  division  of  one  cell  into  two, 
the  contrary  process  occurs,  namely,  the  coalescence  of  two 
cells  to  form  one.  This  is  called  conjugation.  It  is  observed 
among  some  of  the  protozoa,  two  of  these  organisms  becoming 
completely  fused  to  form  one  individual.  A  form  of  conju- 
gation also  occurs  throughout  the  greater  part  of  the  entire 
animal  and  plant  kingdoms  in  connection  with  sexual  repro- 
duction. The  fusion  of  the  female  and  male  gerrn-cells,  the 
ovum  and  spermatozoon  in  animals,  the  ovule  and  pollen  in 
plants,  is  a  case  of  conjugation,  although  here  the  uniting  cells 
are  somewhat  different  from  each  other.  This  form  of  conjuga- 
tion is  evidently  of  profound  significance  in  the  vital  economy, 
though  not  well  understood.  Even  in  the  protozoa  conjuga- 
tion is  perhaps  connected  with  reproduction. 

Sexual  reproduction :  Multicellular  animals  are  developed 
from  a  female  and  a  male  cell,  which  coalesce  and  form  a 
single  cell,  the  fecundated  ovum.  The  spores  from  which 
cryptogamous  plants  develop  are  likewise  fertilized  single 
cells.  Phenogamous  plants  are  developed  in  essentially  the 
same  way ;  the  fully  formed  seeds  are,  however,  multicellu- 
lar,  though  they  can  be  traced  back  to  a  single  fertilized  ovule- 
cell.  The  female  element  before  fecundation  is  termed  the 
ovule;  after  union  with  the  male  element  it  becomes  the  ovum. 
The  male  elements  in  animals  are  the  spermatozoa ;  in  flow- 
ering plants,  the  pollen. 

The  ovule :  The  mammalian  ovule,  as  fully  developed  in 
the  female  ovary,  is  a  comparatively  large  spherical  cell  about 
0.2  millimetre  in  diameter.  It  is  surrounded  by  a  delicate 
membranous  wall,  the  vitelline  membrane.  The  body  of  the 
cell  consists  of  protoplasm  infiltrated  with  a  large  number  of 
minute  fat-globules,  for  the  early  nourishment  of  the  develop- 
ing embryo  ;  this  is  the  vitellus,  or  yolk.  Within  the  vitellus, 
located  excentrically,  is  the  nucleus  of  the  cell,  or  the  germi- 
nal vesicle ;  within  this,  again,  is  the  nucleolus,  or  germinal 
spot. 

Maturation  of  the  ovule  :  Before  or  while  the  ovule  receives 


FERTILIZATION  OF  THE  OVUM.  39 

the  male  element  it  undergoes  certain  changes,  called  matura- 
tion. The  nucleus  of  the  ovule  divides  and  gives  off  a  portion 
of  its  substance,  which  forms  a  small  body,  the  polar  body, 
which  proceeds  to  the  surface  of  the  cell  and  is  there  ex- 
truded. This  process  is  repeated,  a  second  polar  body  being 
given  off  from  the  nucleus  and  expelled  from  the  cell  in  the 

FIG.  10. 


Maturing  ovum  of  physa  (fresh-water  snail)  (Kostanecki  and  Wierzejski).  Above 
is  the  first  polar  body  extruded  from  the  ovule  and  dividing  into  two  bodies. 
Just  beneath  it  is  the  nucleus  of  the  ovule,  dividing  to  form  the  second  polar 
body.  At  the  centre  of  the  ovule  is  the  male  pronucleus  with  its  centrosome 
and  attraction-sphere,  derived  from  the  spermatozoon. 

same  way.  By  this  process  the  nucleus  is  "  reduced/'  or 
divested  of  a  portion  of  its  chromatin,  so  that  when  the  chro- 
matin  of  the  spermatozoon,  also  reduced,  is  united  with  it  the 
number  of  chromosomes  normal  to  the  cells  of  the  species  is 
present.  The  portion  of  the  original  nucleus  now  remaining 
in  the  ovule  is  called  the  female  pronucleus. 

Fertilization  of  the  ovum:  The  ovule  is  not  capable  of  under- 


40  REPRODUCTION  AND  DEVELOPMENT. 

going  further  development  until  the  male  element,  or  sperm-cell, 
is  added  to  it.  This  process  is  called  the  fertilization,  impreg- 
nation, or  fecundation  of  the  ovum.  During  or  after  the  proc- 
ess of  maturation  the  spermatozoon  finds  its  way  to  the  surface 
of  the  ovule,  passes  through  the  vitelline  membrane,  or  through 
a  small  opening  in  it  called  the  micropyle,  and  enters  the  proto- 
plasm, where  it  forms  a  nucleus,  the  male  pronudeus  (Fig.  10). 
The  male  and  female  pronuclei  then  coalesce,  or  at  least  be- 
come apposed,  and  temporarily  disappear,  reappearing  when 
the  cell  undergoes  division.  The  ovum  is  now  fully  formed 
and  capable  of  further  development.  It  is  a  typical  cell, 
endowed  potentially  with  all  the  attributes  of  vitality,  and 
contains  within  its  minute  compass  almost  inconceivable  pow- 
ers of  definite  and  intricate  expansion  and  evolution.  It 
might  seem  at  first  view  that  the  largest  part  of  the  substance 
of  the  fertilized  ovum  was  contributed  by  the  female  parent, 
while  the  contribution  of  the  male  was  comparatively  insig- 
nificant ;  but  of  the  really  vital  substance,  the  chromatin,  the 
male  element  furnishes  as  much  as  the  female,  and  hence  makes 
an  equal  impression  on  the  offspring.  To  explain  the  ina- 
bility of  the  unimpregnated  female  ovule  to  undergo  division, 
it  has  been  suggested  that  it  has  no  centrosome,  and  that  this 
is  supplied  by  the  spermatozoon,  the  addition  of  which  there- 
fore supplies  all  the  conditions  necessary  for  division. 

Development  of  the  embryo :  The  further  development  of 
the  embryo  proceeds  by  mitotic  cell-division.  The  ovum 
divides  into  two  cells ;  each  of  these  into  two  more,  and  so 
on.  Thus  a  mass  of  cells  is  formed,  constituting  the  blasto- 
derm. Soon  the  cells  of  the  blastoderm  develop  so  as  to 
form  two  layers,  the  outer  being  called  the  epiblast,  the  in- 
ner the  hypoblast.  Later  another  layer  of  cells  appears 
between  these  two,  and  is  called  the  mesoblast.  Up  to  a  cer- 
tain point  the  cells  produced  by  repeated  cleavage  are  similar 
to  one  another  ;  but  afterward  differences  of  form  and  purpose 
appear  in  different  situations  according  to  the  organs  and  tis- 
sues into  which  they  are  about  to  develop.  This  development 
of  cells  having  similar  origins  into  dissimilar  cells  is  the  proc- 
ess of  differentiation.  By  the  continued  production  and  dif- 
ferentiation of  the  cells  of  the  epiblast,  hypoblast,  and  meso- 
blast, the  embryo  develops,  and  the  various  organs  gradually 


DEVELOPMENT  OF  THE  EMBRYO.  41 

come  into  existence.  The  details  of  this  process  it  is  the 
province  of  the  science  of  embryology  to  consider. 

Well-defined  tracts  of  the  adult  body  may  be  traced  back  to 
the  three  primary  blastodermic  layers,  and  the  distinctions  of 
origin  thus  made  are  commonly  emphasized  as  of  importance. 
Without  entering  into  minutiae,  the  tissues  derived  from  the 
primary  layers  are  in  general  as  follows : 

From  the  epiblast  are  derived  the  epithelium  of  the  epider- 
mis ;  the  nerve-centres  and  axis-cylinders,  and  the  enamel  of 
the  teeth. 

From  the  hypoblast  is  derived  the  epithelium  of  the  mucous 
membranes  lining  the  alimentary  and  respiratory  tracts  and 
bladder,  and  of  the  glands  tributary  thereto. 

From  the  mesoblast  are  derived  the  corium  of  the  skin  and 
the  tunica  propria  of  mucous  membranes  ;  the  connective-tissue 
structures ;  cartilage,  bone,  the  vascular  and  lymphatic  sys- 
tems, the  blood,  the  muscular  tissues,  the  reproductive  organs, 
and  the  kidneys  and  ureters. 


CHAPTER    IV. 

THE  TISSUES. 

Classes  of  tissues :  Cells  and  intercellular  elements  make 
up  tissues  ;  tissues  make  up  organs.  A  full  knowledge  of  the 
different  varieties  of  tissues  is  essential  to  an  adequate  and 
easy  understanding  of  the  structure  of  organs.  The  simple 
tissues  of  the  human  body  may  be  divided  into  five  classes : 

Epithelium  and  endothelium ; 

Connective  tissue ; 

Muscle ; 

Nerve-tissue ; 

Free  cells  and  body-fluids. 

Of  these  the  first  four  are  made  up  of  fixed  elements ;  the 
last  comprises  the  free  and  fluid  parts  of  the  organism.  These 
classes  are  sharply  distinguished  from  one  another  by  morpho- 
logical and  functional  characters  and  by  the  fact  that  each 
class,  in  general,  is  developed  from  and  in  turn  produces  its 
own  kind  of  cell  and  tissue  exclusively. 

Endothelium  and  Epithelium. 

Location :  The  cells  lining  the  exposed  surfaces  of  the  body 
form  the  class  of  epithelium  and  endothelium. 

Those  lining  the  closed  internal  cavities,  as  the  vessels  and 
serous  sacs,  and  derived  from  the  mesoblast,  are  called  endo- 
thelial  cells. 

Those  lining  the  "  external "  surface  of  the  body  and  the 
channels  and  tracts  continuous  with  it  (that  is,  those  lining  the 
skin,  mucous  membranes,  and  tributary  glands),  also  the 
closed  thyroid  and  other  ductless  glands,  central  canal  of  the 
spinal  cord,  and  ventricles  of  the  brain,  are  called  epithelium. 

Epithelium  consists  almost  entirely  of  cells,  there  being  only 
a  slight  amount  of  intercellular  substance  to  cement  them  to- 
gether. It  is  derived  from  the  epiblast  and  hypoblast,  except 

42 


STRATIFIED  SQVAMOUS  EPITHELIUM. 


43 


the  epithelium  of  the  kidneys,  ureters,  and  sexual  organs, 
which  is  mostly  of  mesoblastic  origin. 

Its  function  is,  over  large  areas,  protective ;  in  the  glands 
it  is  secretory  ;  in  some  tracts,  as  the  intestine,  it  is  not  only 
protective,  but  has  absorbent  functions;  while  ciliated  and 
other  epithelium  serve  special  purposes. 

Varieties  of  epithelium:  Epithelium-cells  may  be  divided 
into  the  following  classes  :  squamous,  columnar,  ciliated,  gob- 
let, glandular,  and  specialized  epithelium.  Some  of  these, 
again,  are  divisible  into  simple  epithelium,  in  which  the  cells 
form  a  single  layer;  and  stratified,  in  which  they  are  arranged 
in  several  layers. 

Simple  squamous  epithelium :  Squamous  epithelium-cells  are 
large,  thin,  flat,  disc-shaped  cells,  each  with  a  large  discoid 
nucleus.  In  simple  squamous  epithelium  the  cells  form  but 
a  single  layer,  and  meet  edge  to  edge.  It  is  not  extensively 
distributed,  occurring  in  the  alveoli  of  the  lungs,  the  capsule 
of  the  Malpighian  bodies  of  the  kidney,  and  a  few  other  situa- 
tions. Endothelium  is  very  similar  to  it. 

FIG. 11. 


Stratified  squamous  epithelium,  oesophagus  of  rabbit  (Dunham),  a,  deeper  layers 
of  rounded  germinal  cells ;  b,  more  superficial  layers  of  flattened  cells ;  c,  sur- 
face layer  of  horny  cells ;  d,  underlying  fibrous  tissue ;  e,  papillary  projection 
from  the  fibrous  layer. 

In  stratified  squamous  epithelium  the  cells  form  several 
layers  (Fig.  11).  Those  on  the  surface  are  flattened  and 
squamous,  overlapping  one  another  at  the  edges.  The  cells 
of  the  lower  layers  are  cuboidal  or  spheroidal ;  they  become 


44  THE  TISSUES. 

gradually  flattened  toward  the  surface,  and  are  germinal  cells 
which  ultimately  become  squamous.  This  variety  is  of  exten- 
sive distribution,  forming  the  epidermis  of  the  skin  and  the 
epithelial  layer  of  the  conjunctiva,  mouth,  part  of  the  pharynx 
and  larynx,  oesophagus,  vagina,  and  portions  of  the  urethra. 

The  'epithelium  lining  the  bladder,  ureters,  and  pelvis  of 
the  kidneys  is  a  variety  of  stratified  squamous  epithelium 
sometimes  called  transitional  epithelium  (Fig.  12).  The  num- 
ber of  layers  of  cells  is  few,  forming  a  sort  of  intermediate 

FJG.  12. 


Transitional  epithelium,  bladder  of  mouse  (Dogiel). 

or  transitional  variety  between  the  simple  and  stratified  types. 
The  lower  cells  become  quickly  changed  into  the  flattened 
surface  cells. 

Columnar  epithelium — non-ciliated:  Columnar  epithelium- 
cells  are  elongated,  columnar,  or  prismatic  in  shape,  arranged 
on  a  basement-membrane  perpendicular  to  it,  with  one  end  di- 
rected outward.  Sometimes  they  are  shorter  and  more 
cuboidal. 

When  they  form  a  single  layer  they  constitute  simple  col- 
umnar epithelium  (Fig.  13),  which  occurs  throughout  the 
stomach  and  intestine,  in  some  gland-ducts,  covering  the  ovary, 
and  in  portions  of  the  male  urethra  and  seminal  tracts. 

Non-ciliated  stratified  columnar  epithelium,  in  which  the  cells 


GLANDULAR  EPITHELIUM. 


45 


are  in  several  layers  (the  outer  only  being  columnar),  occurs 
in  the  olfactory  nasal  membrane  and  a  portion  of  the  vas 
deferens. 

Columnar  epithelium — ciliated  :  A  variety  of  epithelium  in 


FIG.  13. 


Simple  columnar  epithelium  and  goblet  cells,  from  the  intestine,    Shows  the  stri- 
ated free  cuticular  margin  of  the  cells  in  this  situation. 

which  the  exposed  surfaces  or  ends  of  the  cells  are  covered 
with  cilia,  which  in  life  are  in  characteristic  wave-like  motion. 

Simple  ciliated  epithelium    occurs  in    the  Fallopian    tubes, 
uterus,  central  canal  of  the  spinal  cord,  and  brain  ventricles. 

In  stratified  ciliated  epithelium  (Fig.  14)  the  cells  form  seve- 
ral layers.     Only  those  of  the  outer  layer  are  columnar  and 
ciliated ;   those  of  the  lower 
layers,  the  germinal  cells,  are  FIG.  14. 

rounded  or  pear-shaped,  be- 
low and  between  the  columnar 
cells,  into  which  they  ulti- 
mately develop.  This  variety 
covers  the  respiratory  tract, 
Eustachian  tubes,  and  epidid- 
ymis. 

Goblet  epithelium-cells  (Fig. 
13)  are  large  elliptical  or  pyri- 
form  cells,  with  their  larger  ciliatedcolumnar  epithelium  (stratified)) 

ends  outward  and  their  nuclei        from  trachea,  showing  ciliary  wave. 

near  their  bases.     They  occur 

scattered  among  columnar  epithelium-cells.  Their  bodies 
have  a  clear  unstained,  distended  appearance,  being  filled  with 
a  mucinous  substance  which  they  secrete  and  discharge  on  the 
surface  of  the  mucous  membrane. 

Glandular  epithelium   is   that   which   forms   the   secreting 


46  THE  TISSUES. 

portion  of  glands.  The  cells  are  in  general  spheroidal  or 
polyhedral,  but  vary  in  shape  in  different  situations. 

Specialized  epithelium :  In  some  situations  epithelium-cells 
become  modified  in  various  ways  different  from  those  above 
mentioned,  as  the  pigmented  epithelium  of  the  retina  and  else- 
where, and  the  so-called  neuro-epithdmm  occurring  in  certain 
sensory  organs,  the  retina,  ear,  tongue,  and  olfactory  mem- 
brane. 

Endothelium :  The  closed  internal  cavities  of  the  body — 
the  vascular  channels,  serous  cavities  (as  the  pleura,  peri- 
toneum, and  pericardium),  synovial  membranes,  and  lymph- 
spaces — are  lined  with  endothelium  (Fig.  15).  Endothelium 

FIG.  15. 


.-,• 


Endothelial  lining  of  small  vein  and  capillary  (Engelmann). 

is  distinguished  from  epithelium  mainly  in  being  of  meso- 
blastic  origin.  Morphologically  it  is  similar  to  simple 
squamous  epithelium,  consisting  of  a  single  layer  of  polygonal 
flat  nucleated  cells,  smooth  and  shiny,  which  meet  edge  to 
edge  by  oftentimes  sinuous  or  serrated  margins.  Endothelium- 
cells  merge  into  the  flattened  type  of  connective-tissue  cells, 
with  which  they  are  genetically  related. 


CONNECTIVE  TISSUE.  47 

Connective  Tissue. 

Connective  tissue  is  distributed  everywhere  throughout  the 
body  beneath  the  outer  epithelial  layer.  It  forms  a  support- 
ing and  connecting  framework  for  the  parts  of  the  organism, 
and  to  this  end  it  envelops  and  penetrates  all  the  interior 
organs  and  structures.  It  permeates  the  organism  so  com- 
pletely that  if  all  the  other  tissues  were  removed  the  connec- 
tive-tissue framework  would  still  form  a  complete  mould  of 
the  body  and  its  organs.  It  originates  from  the  mesoblast, 
except  the  neuroglia  of  the  nerve-centres,  which  is  epiblastic. 
Like  other  tissues,  it  is  made  up  of  cells  and  non-cellular 
elements,  but  is  peculiar  in  that  the  non-cellular  portions 
largely  predominate,  as  naturally  follows  from  their  constitut- 
ing the  main  framework  of  the  body. 

The  connective-tissue  cells,  while  differing  in  various  situa- 
tions, have  a  fundamental  morphological  and  genetic  simi- 
larity. 

The  extracellular  elements  serve  mechanical  purposes,  and 
are  not  endowed  with  vitality ;  they  are  produced  by  the 
connective-tissue  cells.  The  most  specialized  and  generally 
distributed  of  the  extracellular  elements  are  certain  fibres, 
which  are  of  two  kinds,  white  fibres  and  yellow  elastic  fibres. 
Other  intercellular  materials  are  an  interstitial  mucinous  or 
gelatinous  substance  especially  found  in  young  connective 
tissues  (as  mucous  tissue),  the  matrix  of  hyaline  cartilage, 
and  the  mineral  matter  in  bone. 

Connective -tissue  cells  are  of  one  general  type,  though 
varying  much  in  different  situations.  The  forms  associated 
with  fibrous  tissues  are  sometimes  called  "fibroblasts." 
Connective-tissue  cells  are  sometimes  round  or  spherical, 
small  and  prominently  nucleated  ;  such  cells  occur  only  in 
young,  growing,  or  embryonal  forms  of  connective  tissues. 

The  mucous  cell  is  another  form  of  young  or  embryonal 
connective-tissue  cell ;  it  is  a  fiat  nucleated  cell  of  irregular 
stellate  shape,  with  its  pointed  processes,  three  or  four  in 
number,  prolonged  into  fine  filaments  which  anastomose  with 
similar  processes  from  neighboring  cells. 

In  some  situations,  especially  in  fibrous  tissues,  the  connec- 
tive-tissue cells  are  fusiform  in  shape ;  in  some  they  are 
stellate ;  in  others,  as  in  basement-membranes  and  the  cells 


48 


THE  TISSUES. 


lining  retiform  tissue  and  lymph-spaces,  they  are  flattened  like 
endothelium,  with  which  they  are  closely  related  ;  sometimes 
they  are  lamellar,  as  in  tendon-cells  ;  or  they  may -be  altogether 
irregular. 

In  general,  connective-tissue  cells  are  small  flattened  or 
elongated  cells,  with  prominent  nuclei  and  relatively  small 
bodies,  and  often  wirh  processes  ;  they  are  polymorphous  and 
adaptable  to  the  situations  in  which  they  are  placed.  Some- 
times they  are  pigmented,  such  cells,  stellate  or  irregular, 
occurring  in  the  choroid,  pia  mater,  and  in  amphibia. 
Some  connective-tissue  cells  are  granular,  as  precursors  of  fat- 
cells. 

Fat-cells  are  large  spherical  connective-tissue  cells  distended 
with    fat.        Odontoblasts,    cartilage-cells,    and    bone-cells   are 
forms   of  connective-tissue   cells,    and   neuroglia-cells   differ 
chiefly  in  their  epiblastic  origin. 
Plasma-cells  occurring  in  areo-  FIG.  17. 

lar    tissue     contain    numerous 
vacuoles  and  vary  in  form. 

Mast-cells     are     large    cells 

FIG.  16. 


White  fibres,  teased  to  show  indi- 
vidual nbrillse  (Dunham). 


Yellow  elastic  fibres  from  subcutane- 
ous areolar  tissue  (Schafer). 


twenty  to  thirty  micromillimetres  in  diameter,  containing 
coarse  basophile  (y)  granules,  and  irregular  pale-staining 
nuclei ;  they  are  occasionally  found  in  areolar  tissue. 


MUCOUS  TISSUE.  49 

Wandering  cells,  cells  which  are  free  and  capable  of  moving 
about  in  areolar  tissue,  are  really  leukocytes  or  lymph- eel  Is, 
and  belong  to  the  class  of  free  cells. 

The  white  fibres  consist  of  very  fine  colorless  fibrillae 
cemented  together  in  coarser  fibres  (Fig.  16).  They  may  be 
arranged  in  an  interlacing  network  or  parallel  in  bundles,  and 
often  present  a  wavy  appearance.  The  fibrils  do  not  branch. 
They  swell  and  become  indistinct  when  treated  with  acetic 
acid,  often  showing  constrictions.  They  yield  gelatin  on 
boiling.  They  are  characterized  by  unyielding  strength,  and 
occur  in  tendons,  ligaments,  etc.,  where  tenacity  and  firmness 
are  required. 

The  yellow  elastic  fibres  (Fig.  17)  are  yellowish,  highly 
refractive,  branching  fibres,  fine  or  coarse,  forming  bundles  or 
membranous  interlacing  networks.  They  yield  elastin,  not 
gelatin,  and  stain  differentially  with  orcein.  When  divided,  the 
freed  ends  curl  up.  They  are  characterized  by  elasticity,  and 
are  widely  distributed,  occurring  in  especial  abundance  in  the 
ligamentum  nuchae  of  animals,  ligamenta  subflava,  blood- 
vessels, and  in  yellow  elastic  cartilage. 

Two  theories  are  held  as  to  the  development  of  the  fibres, 
white  and  yellow :  one  is  that  they  are  produced  by  a 
transformation  of  the  protoplasm  of  the  connective-tissue 
cells  ;  the  other,  probably  more  generally  true,  is  that  they 
are  not  transformed  cells,  but  develop  in  the  mucinous  inter- 
cellular matrix  by  a  sort  of  secretory  process,  under  the 
agency  of  the  cells. 

Varieties  of  connective  tissues:  According  to  the  varving 
forms  and  proportions  of  the  constituent  elements,  there  are 
many  varieties  of  connective  tissues,  merging  imperceptibly 
into  one  another  without  sharp  dividing  lines.  The  following 
best-marked  types  may  be  mentioned  : 

Mucous  tissue;  Tendons;    * 

Areolar  tissue  ;  Retiform  tissue  ; 

White  fibrous  tissue  ;  Cartilage  ; 

Yellow  elastic  tissue  ;  Bone  ; 

Membranes ;  Dentine ; 

Adipose  tissue ;  Neuroglia. 

Mucous  tissue  (Fig.  18)  consists  of  mucous  cells,  flattened 

4— Hist. 


50 


THE  TISSUES. 


stellate  cells  with  fine  anastomosing  processes,  forming  an 
open  reticulum,  the  meshes  of  which  are  filled  with  a  semi- 
fluid mucinous  matrix.  It  is  a  soft  gelatinous  tissue.  It  is 
an  embryonal  or  early  stage  of  connective  tissue,  becoming 
later  more  firm  by  the  development  of  fibres  in  the  intercel- 
lular substance.  It  occurs  in  the  umbilical  cord  and  other 


FIG.  18. 


if  ^'-ir  *r&>  -^m t 


Mucous  or  embryonic  connective  tissue  (Bohm  and  Davidoff  ). 

situations  in  the  early  embryo,  but  in  the  adult  only  in  the 
vitreous  body  of  the  eye  and  in  mucous  tumors. 

Areolar  tissue  (often  somewhat  ambiguously  called  "cellular 
tissue  ")  is  unloose  network  of  white  and  yellow  fibres  con- 
taining connective-tissue  cells,  fat-cells,  wandering  cells,  and 
blood  and^ymphatic  vessels  (Fig.  19.)  The  open  spaces,  or 
areolse  (whence  the  name  of  the  tissue),  are  filled  with  lymph. 
It  is  a  loose  delicate  shining  tissue,  widely  distributed,  found 
ecially  beneath  the  skin  and  mucous  membranes,  and 
pjjrts  to  move  somewhat  upon  each  other. 
of  one  or  another  constituent  it  passes 


\ 


YELLOW  ELASTIC  TISSUE. 


51 


gradually  into  fibrous,  adipose,  or  other  varieties  of  connec- 
tive tissue. 

White  fibrous  tissue  is  that  in  which  the  white  fibres  pre- 
dominate, forming  a  tough,  dense,  inelastic  tissue.  Connec- 
tive-tissue cells,  fusiform,  or  flat  and  clasping  the  fibrous 
fasciculi,  are  scattered  among  the  wavy  fibres,  more  numerous 

FIG.  19. 


Subcutaneous  areolar  tissue,  from  rabbit,  showing  white  and  elastic  fibres  and 
connective-tissue  cells  (Schafer).  c,  developing  fusiform  and  stellate  cells; 
c',  flattened  cell ;  /,  elongated  cell ;  g,  wandering  cell ;  p,  plasma-cells. 

when  the  tissue  is  young,  less  numerous  or  even  almost 
absent  in  old  tissues.  It  is  widely  distributed,  forming  tough 
fascia?,  aponeuroses,  ligaments,  capsules  and  trabeculse  of 
organs,  and  the  like. 

Yellow  elastic  tissue  is  that  in  which  elastic  fibres  predomi- 
nate, as  in  the  ligamenta  subflava  and  bloodvessels,  structures 
characterized  by  elasticity  and  resiliency.  The  l*gamentum 
nuchae  of  certain  animals  consists  mainly  of  coarse. polygonal 
yellow  fibres,  with  a  few  scattered  white  fibres  or  cells. 
Arteries  contain  much  elastic  tissue,  largely  in  the  form  of 
elastic  plates,  fibrous  networks,  or  perforated  membranes. 

Membranes:    Connective  tissue  often  forms  distinct  mem- 


52 


THE  TISSUES. 


FIG.  20. 


branes,  as  in  the  capsules  surrounding  organs  and  the  corium 
of  the  skin.  These  are  often  fibrous  tissue,  made  up  of  inter- 
lacing fibers ;  in  other  cases,  especially  in  the  basement-mem- 
branes which  support  epithelium,  they  consist  of  flattened 
connective-tissue  cells  joined  edge  to  edge  in  a  single  layer. 

Adipose  or  fatty  tissue  (Fig.  20)  occurs  in  large  masses 
under  the  skin,  in  the  omentum,  about  the  viscera,  especially 
the  kidneys  and  heart,  and  elsewhere.  The  cells  are  large, 

distended  spheres  of  fat,  which 
has  been  accumulated  in  the 
cell-body  until  the  original  pro- 
toplasm has  been  compressed 
into  a  thin  atrophied  membrane 
enveloping  the  fat,  and  the 
nucleus  has  been  pushed  out  into 
the  periphery.  The  cells  are 
spherical  in  shape,  and  are 
packed  together  in  masses,  with 
inconspicuous  fibres  between. 
Fatty  tissue  merges  into  areolar 
tissue  in  which  the  connective- 
tissue  cells  become  filled  with 
fat  and  crowded  together. 

Retiform  tissue  (Fig.  21)  con- 
sists of  a  reticulum  of  fine  interlacing  fibres,  covered,  espe- 
cially at  the  intersections,  with  flat  stellate  endothelioid  con- 
nective-tissue cells.  This  tissue  forms  the  framework  of  lym- 
phoid or  adenoid  tis&ue,  as  in  lymph-follicles  and  glands,  in 
which  the  open  spaces  of  the  reticulum  are  filled  with  lymph 
and  lymphoid  corpuscles,  which  crowrd  the  meshes  and  obscure 
the  network  ;  these  lymphoid  corpuscles  belong  to  the  class 
of  free  cells  and  are  not  fixed  in  the  spaces.  The  framework 
of  the  spleen  is  of  a  similar  character.  Retiform  tissue  may 
be  regarded  as  an  open  sustentacular  tissue  for  containing 
lymph-corpuscles  and  lymph.  The  term  "retiform"  as  here 
used  applies  only  to  the  connective-tissue  framework,  and  is 
not  taken  to  include  the  lymph-corpuscles  or  as  a  synonym  of 
lymphoid  tissue. 

Cartilage  is  a  specialized  form  of  connective  tissue  consist- 
ing of  cartilage-cells,  which  are  modified  connective-tissue 


Adipose  tissue.  Crystals  of  fatty 
acids  are  represented  in  two  of 
the  cells. 


HYALINE  CARTILAGE. 


53 


cells,  imbedded  in  an  abundant  matrix.     .According  to  the 
nature  of  the  matrix,  cartilage  is  of  four  kinds,  hyaline  carti- 


FIG.  21. 


Retiform  tissue  (Ribbert). 

lage,  white  fibro-cartilage,  yellow  elastic  cartilage,  and  cellu- 
lar cartilage. 

FIG.  22. 


Hyaline  cartilage. 


Hyaline  cartilage  (Fig.  22)  occurs  in  the  costal  cartilages, 
the  articular  ends  of  bones,  the  nasal  cartilaginous  septum, 


54 


THE  TISSUES. 


the  larger  cartilages  of  the  larynx,  the  trachea  and  bronchi, 
and  in  the  embryo  is  the  precursor  of  most  of  the  bones.  The 
cells  are  prominent  and  rounded,  with  large  nuclei  and  dis- 
tinct capsules,  and  are  imbedded  in  an  apparently  homogeneous, 
hyaline,  tough  matrix,  which  yields  chondrin.  Instead  of 
being  really  homogeneous,  the  matrix  is  said  to  have  a  delicate 
fibrillar  structure.  The  means  or  channels  by  which  nutrient 
fluids  can  penetrate  to  the  interior  of  hyaline  cartilage  for  its 
nutrition  are  not  known.  The  cartilage-cells  divide  in  two 
within  the  capsule  of  the  parent-cell,  which  is  thus  as  it  were 
cast  off,  and  each  daughter-cell  then  acquires  a  new  capsule. 
By  the  repetition  of  this  process  t\vo  or  three  generations  of 
cells  may  sometimes  be  found  within  the  remains  of  the  cast- 
off  capsule  of  the  single  original  parent-cell.  The  capsules 
thus  cast  off  are  gradually  transformed  into  the  matrix,  which 
is  partly  developed  in  this  way.  The  ground-substance  near 
the  cells  stains  differently  from  that  more  remote.  Owing  to 
their  mode  of  division  the  cells  in  costal  cartilage  tend  to 
occur  in  groups  ;  in  articular  cartilage  they  form  rows  perpen- 
dicular to  the  surface. 

Some  of  the  cartilages  are  surrounded  by  a  fibrous  mem- 
brane, the  perichondrium  j  containing  fusiform  or  flattened  con- 
nective-tissue cells.  The  lowermost  of  these  cells  take  on  the 
characters  of  cartilage-cells,  become  thicker  and  more  rounded, 
and  the  edge  of  the  cartilage  shows  a  gradual  transition  from 
these  cells  to  the  typical  cartilage-cells  in  the  interior.  In 
this  manner  the  cartilage  is  produced  or  grows  from  the  lower 
layer  of  the  perichondrium. 

FTO.  23. 


Fibro-cartilage,  from  human  inter  vertebral  disc  (Schaferj. 

White  fibre-cartilage  (Fig.  23)  forms  the  intervertebral  discs 
and  other  cartilages  entering  into  the  construction  of  certain 


CELLULAR   CARTILAGE. 


55 


joints.  It  consists  of  a  dense  white  fibrous  matrix  in  which 
cartilage-cells  are  imbedded.  According  to  the  character  of 
the  cells,  it  exhibits  all  gradations  to  ordinary  white  fibrous 
tissue. 

Yellow  elastic  cartilage  (Fig.  24)  occurs  in  the  auricles, 
Eustachian  tubes,  epiglottis,  portions  of  the  arytenoid  carti- 
lages, and  the  small  cartilaginous  bodies  near  the  latter.  It 


Elastic  cartilage,  from  human  auricle  (Bohm  and  Davidoff). 

is  characterized  by  elasticity  and  resiliency.  Its  matrix 
mainly  consists  of  a  network  of  elastic  fibres  the  meshes  of 
which  contain  the  cartilage-cells. 

Cellular  cartilage  is  a  primitive  form  of  cartilage,  and  con- 
sists of  cartilage-cells  cemented  together  in  a  dense  cellular 
mass  with  scarcely  any  intercellular  matrix.  It  occurs  in 
man  only  at  an  embryonic  period,  making  up  the  primitive 
vertebras;  it  is  found  in  the  ear  of  mice  and  some  other  animals. 


56 


THE  TISSUES. 


Bone  (Fig.  25)  is  another  specialized  form  of  connective 
tissue,  made  up  of  bone-cells  or  corpuscles  and  an  intercellular 
matrix  impregnated  with  calcareous  salts.  It  occurs  in  two 
forms,  compact,  making  up  the  greater  part  of  long  bones  and 
the  outer  part  of  all  bones,  dense  and  solid  ;  and  cancellous,  in 
the  ends  and  lining  the  medullary  canal  of  long  bones  and  in 
the  interior  of  all  other  bones  ;  it  is  loose  and  spongy,  consisting 
of  spaces  (cancelli)  separated  by  thin  osseous  walls. 

The  material  of  which  bone  is  composed  is  divisible  into 
two  kinds,  organic  and  mineral.  By  burning,  the  organic 
portion  is  destroyed,  leaving  the  mineral  portion  ;  while  on 

FIG.  25. 


Cross-section  of  compact  bone,  showing  Hayersian  systems,  bony  lamellae, 
lacunae,  and  canaliculi  (Klein). 

treatment  with  acid  the  mineral  matter  is  removed,  or  the 
bone  is  "  decalcified,"  the  organic  material  remaining  as  a 
tough  flexible  substance. 

The  bone-cells  are  modified  connective-tissue  cells,  of  a 
flattened  shape,  with  numerous  fine  processes  projecting  from 
them  in  all  directions.  The  bodies  of  the  cells  occupy  the 
spaces  called  the  lacunce,  while  the  processes  occupy  the 
canaliculi.  • 

The  matrix  consists  of  dense  fibrous  organic  matter  (such  as 
appears  in  decalcified  bone)  impregnated  with  calcareous  salts. 
It  is  arranged  in  series  of  concentric  lamella1,  which  form  four 


BOXE-MARRO  W.  57 

kinds  of  systems — Haversian,  peripheral,  peri-medullary,  and 
intermediate. 

A  Havcr*ian  system  consists  of  a  series  of  concentric 
lamellae  surrounding  a  Haversian  canal,  a  small  round  canal 
containing  blood-  and  lymphatic-vessels  and  marrow,  running 
generally  lengthwise  the  bone,  and  communicating  and  con- 
tinuous with  the  interior  marrow- cavity.  Between  the 
adjacent  lamellae  at  short  intervals  are  spaces  called  lacunae, 
occupied  by  the  bone-cells;  connecting  the  lacunae  are  numer- 
ous minute  passages  called  canaliculi,  occupied  by  the  processes 
of  the  cells.  The  canaliculi  afford  communication  for  the 
passage  of  nutrient  fluids  from  the  Haversian  canals  through- 
out the  adjacent  lamellae. 

The  peripheral  or  circumferential  lamella?  are  a  series  of 
subperiosteal  lamellae,  similar  to  the  Haversian  lamellae, 
surrounding  the  entire  bone.  In  places  there  are  fibres 
piercing  the  peripheral  lamellae  at  right  angles — perforating 
fibres,  or  fibres  of  Sharpey. 

The  peri-medullary  lamella?  are  a  similar  series  surrounding 
the  marrow-cavity. 

The  intermediate  or  interstitial  lamella?  are  scattered  irreg- 
ularly about  in  the  bone  substance,  and  are  the  remains  of  old 
systems  that  in  the  course  of  the  growth  of  the  bone  have 
been  partially  removed. 

The  periosteum,  the  covering  membrane  of  bone,  is  com- 
posed of  two  layers:  an  outer  firm  fibrous  protective  layer; 
and  an  inner  loose  layer  well  supplied  with  blood  and  connec- 
tive-tissue cells  (or  osteoblasts),  which  has  important  functions 
in  the  growth  of  bone  and  is  hence  called  the  osteogenetic 
layer. 

Bone-marrow  :  The  cavities  in  bone — the  cancelli  of  spongy 
bone,  the  medullary  or  marrow-cavities  of  long  bones,  and 
the  Haversian  canals — contain  a  soft  vascular  tissue,  the 
ni<trroir.  which  is  of  two  kinds,  red  and  yellow. 

Red  marrow  occurs  in  cancellous  bone  in  the  adult,  in  all 
bone  in  the  young.  It  consists  of  delicate  connective  tissue, 
a  rich  vascular  network  including  large  venous  sinuses, 
quantities  of  cells  called  marrow-cells,  and  fat-cells.  The 
marrow-cells  are  of  several  kinds,  chief  among  which  are  :  («) 
plastic  rounded  connective-tissue  cells,  many  of  \vhich  in 


58  THE  TISSUES. 

growing  bone  become  osteoblasts  and  aid  in  bone-formation  ; 
(b)  large  multinucleated  giant  cells,  or  inyeloplaxes,  which  are 
probably  osteoclasts  and  effect  bone-  absorption  ;  (c)  crytkro- 
blasts,  free  nucleated  cells,  colored  by  and  containing  haemo- 
globin, probably  connected  with  the  development  of  red  blood- 
corpuscles  ;  and  (d)  cells  containing  oxyphile  granules,  re- 
sembling the  eosinophile  leukocytes  of  normal  blood; 
other  cells  resembling  the  myelocytes  which  appear  in  the 
blood  in  certain  abnormal  conditions  ;  and  other  forms  of  leuk- 
ocytes. 

Yellow  marrow  occurs  in  the  medullary  cavities  of  long 
bones  and  larger  cancelli  of  the  adult.  It  is  similar  to  red 
marrow,  except  that  it  contains  large  quantities  of  fat-cells,  or 
marrow-cells  distended  with  fat,  to  which  it  owes  its  oiliness 
and  straw  color. 

The  function  of  marrow  is  partly  to  form  bone-substance, 
partly  to  form  red  blood-corpuscles.  Genetically  the  marrow 
is  a  continuation  or  offshoot  of  the  osteogenetic  periosteal 
layer. 

The  development  of  bone  takes  place  by  two  methods,  carti- 
laginous and  membranous. 

Cartilaginous  bone-formation  (Fig.  26) :  Most  of  the  bones, 
especially  the  long  bones,  are  in  the  embryo  first  formed  of 
hyaline  cartilage.  The  conversion  of  this  cartilage  into  bone 
constitutes  the  cartilaginous  method  of  bone-formation.  In 
these  embryonic  cartilages  bone-formation  begins  at  definite 
points,  the  "  centres  of  ossification."  The  cartilage-cells 
enlarge  and  proliferate  abundantly,  and  arrange  themselves  in 
longitudinal  rows,  with  septa  between  the  rows  composed  of 
the  hyaline  matrix.  The  longitudinal  spaces  inclosed  by  these 
septa  and  filled  with  cartilage-cells  are  called  the  primary 
areolce.  These  septa  soon  become  calcified  by  the  deposition 
in  them  of  lime  salts.  From  the  osteogenetic  layer  of  the 
periosteum  loops  of  bloodvessels  then  grow  into  the  cartilage, 
accompanied  by  connective-tissue  cells,  and  by  large  multi- 
nucleated  cells  called  osteoclasts,  which  have  the  power  of 
absorbing  the  cartilage  and  bone-substance  and  thus  open 
passages  and  spaces.  The  cartilage-cells  filling  the  primary 
areolse  disappear,  and  communications  are  made  between  the 
areolse  by  perforations  through  their  calcified  walls,  though 


MEMBRANOUS  BONE-FOEMATIOy. 


59 


FIG.  26. 


these  walls  are  only  partially  absorbed.  The  larger  spaces 
thus  formed  are  termed  secondary  areolce.  Connective-tissue 
cells  now  deposit  themselves  on  the  calcified  walls  of  the 
secondary  areolse  and  become  osteoblasts,  or  bone-formers. 
They  secrete  a  layer  of  bony  - 
substance,  in  which  they  and 
their  processes  become  buried  ; 
they  thus  become  bone-cells, 
in  lacuna?,  with  their  proc- 
esses in  canal  iculi.  When 
one  layer  of  bone  is  thus  de- 
posited, other  osteoblasts  be- 
come fixed  on  the  new  sur- 
face and  form  another  layer. 
This  process  proceeds  from 
the  periphery  of  the  spaces 
inward,  until  only  a  small 
passage  is  left,  the  Haversian 
canal,  the  surrounding  lamellae 
constituting  a  Haversian  sys- 
tem. The  formation  of  bone 
proceeds  in  this  manner  away 
from  the  centres  of  ossification; 
hence  there  are  layers  of  grow- 
ing cartilage  intervening  be- 
tween the  different  ossifying 
areas,  as  between  the  shaft 
and  the  epiphyses  of  long 
bones.  .Not  until  the ^  bone  Development  of  bone  cartilaginous 

attains     its     lull      growth      are  method  ( Klein). 

these  intervening  cartilagi- 
nous portions  fully  converted  into  bone.  The  bone  formed 
by  the  cartilaginous  method  is  temporary,  being  subsequently 
removed  and  renewed  by  the  membranous  method ;  while 
the  interior  of  long  bones  becomes  excavated  to  form  the 
marrow  cavities. 

Membranous  bone-formation :  Some  of  the  bones,  as  the  flat 
bones  of  the  skull,  are  preceded  in  the  embryo  by  white 
fibrous  membranes.  The  conversion  of  these  into  bony  tissue 
(intramembranous  bone-formation)  and  the  formation  of  bone 


60  THE  TISSUES. 

by  the  osteogenetic  layer  of  the  periosteum  (subperiosteal  bone-- 
formation), which  are  substantially  identical  processes,  con- 
stitute the  membranous  method  of  bone-formation.  All  per- 
manent bone  is  formed  in  this  way.  The  process  begins  with 
a  deposition  of  osseous  matter  upon  some  of  the  fibres,  a  por- 
tion of  the  connective-tissue  cells  assuming  the  function  of 
Gsteoblasts.  A  bony  reticulum  is  thus  formed,  in  the  meshes 
of  which  bone-formation  is  continued  by  the  osteoblasts. 
Along  with  the  formation  of  bone,  absorption,  replacement, 
and  remodelling  of  the  bone  constantly  go  on.  Osteoclasts 
excavate  spaces  in  the  bone  previously  laid  down,  in  which 
new  Haversian  systems  are  formed.  The  remains  of  old 
Haversian  and  peripheric  lamella  thus  partially  destroyed 
constitute  the  interstitial  lamellae.  The  spaces  occupied  by 
osteoclasts  are  called  Howship's  lacunce.  In  the  bones  which 
develop  from  membrane  a  membranous  portion  persists  and 
continues  to  grow  between  the  ossifying  areas  or  at  the 
margins,  until  the  bones  attain  their  full  growth,  when  they 
are  completely  ossified. 

Muscle. 

The  muscle-cells  are  specialized  cells  having  the  property  of 
contractility  highly  developed.  Their  function  is  motor,  to 
effect  the  motions  of  the  body.  Muscle  is  derived  from  the 
mesoblast.  Muscular  tissue  is  mainly  made  up  of  the  cellular 
elements,  the  intercellular  substance  being  scanty  and  incon- 
siderable. There  are  three  varieties  of  muscle-cells : 

Striated,  or  voluntary ; 

Cardiac ; 

Involuntary,  or  non-striated. 

Striated  or  striped  muscle  (Figs.  27,  28)  makes  up  all  the 
voluntary  muscles  of  the  body.  The  cells  are  very  much 
elongated  protoplasmic  fibers,  generally  10  to  50  micromilli- 
metres  in  diameter,  and  20  to  40  millimetres  long,  or  even 
longer.  In  shape  the  cells  or  fibres  are  cylindrical  or  pris- 
moidal,  slightly  fusiform,  with  tapering  or  blunt  rounded 
extremities  ;  in  cross-section  they  are  usually  rather  polygonal. 
Each  cell  is  inclosed  in  a  delicate  homogeneous  separable 
envelope,  the  sarcolemma.  The  fibres  are  usually  straight  and 


STRIATED    OR  STRIPED   MUSCLE.  61 

unbranched,but  in  occasional  situations  they  branch  and  anasto- 
mose.   Each  cell  has  many  oval  nuclei,  arranged  with  their  long 
axis  longitudinal  to  the  cell,  situated  in  mammals  just  under- 
neath the  sarcolemma.     The  body  .of 
the  cell  under  moderate  magnification  FIG.  27. 

exhibits  characteristic  transverse  striae 
or  stripes,  consisting  of  delicate  alter- 
nately dark  and  light  lines. 

The  fibres  are  arranged  parallel  to 
one  another,  with  overlapping  ends.  Portiou  oi  str 
They  are  grouped  in  bundles  or  fas- 
ciculi, all  of  which  bound  together  in  fibrous  sustentacular 
tissue  make  up  an  entire  muscle.  The  connective  tissue 
surrounding  and  enclosing  the  entire  muscle  is  called  the  epi- 
mysium;  that  enveloping  the  separate  fasciculi  is  called  the 
perimysium ;  while  the  delicate  and  scanty  connective  tissue 
within  the  fasciculi  among  the  individual  muscle-cells  is  the 
endomysium. 

The  sarcolemma  of  each  fibre  is  connected  with  the  endo- 
mysial  tissue,  and  through  this  with  the  tendon.  Thus  each 
cell  when  it  contracts  exerts  more  or  less  direct  traction  on 
the  tendon.  The  muscle-fibres  are  richly  supplied  with  blood 
by  a  capillary  network  in  the  endomysium.  On  the  surface 
of  each  fibre  is  a  flattened  nerve-terminal. 

The  minute  structure  of  striated  muscle  is  very  difficult  to 
make  out  and  has  not  been  satisfactorily  determined,  and 
authorities  are  not  agreed  in  their  interpretations  of  the  ap- 
pearances presented. 

The  appearance  of  cross-striation  is  produced  by  alternating 
dark  and  light  discs  or  segments  in  the  substance  of  the 
muscle-cells.  By  treatment  with  weak  acids  these  segments 
can  be  separated  from  one  another  in  the  form  of  transverse 
discs.  The  individual  fibres  also  exhibit  a  longitudinal  striation 
as  well  as  transverse,  and  by  treatment  with  alcohol  and  teas- 
ing can  be  broken  up  into  fine  longitudinal  fibrillce ;  these 
fibrillse  are  arranged  in  bundles,  called  fields  of  Cohnheim. 
The  protoplasm  of  the  muscle-cell  is  made  up  of  two  parts, 
a  dark  sarcous  substance  ("  anisotropic,"  or  doubly  refracting) 
and  a  colorless,  hyaline,  probably  semifluid  substance  ("  iso- 
tropic,"  or  singly  refracting),  sometimes  called  sarcoplasm. 


62 


THE  TISSUES. 


FIG.  28. 


These  two  substances  make  up  the  dark  and  light  portions, 
respectively,  of  voluntary  muscle.  On  close  examination  the 
light  or  clear  transverse  segments  are  found  to  be  divided 
into  two  discs  by  a  delicate  transverse  line,  by  some  consid- 
ered to  be  a  definite  membrane  and  called  the  membrane  of 
Krause,  and  by  others  regarded  as  a  row  of  minute  granules, 
called  Dobie?s  granules. 

The  transverse  discs  separated  by  the  "  membrane  of 
Krause"  are  called  sarcous  discs  or  compartments;  each  is 

composed  of  a  dark  segment  with 
half  of  the  adjacent  light  segment 
on  each  side.  The  dark  portion  of 
each  sarcous  disc,  again,  is  not 
homogeneous,  but  is  made  up  of 
minute  dark  longitudinal  rods,  or 
sarcous  elements,  separated  by  the 
light  substance,  or  sarcoplasm.  The 
sarcous  elements  of  adjacent  discs 
correspond  to  one  another  and  with 
the  intervening  granules  of  Dobie, 
so  as  to  form  the  continuous  lon- 
gitudinal fibrillse.  The  appear- 
ances above  described  are  those 
of  relaxed  or  extended  muscle. 

When  the  muscle  contracts  the  fibres  become  shorter  and 
thicker;  the  sarcous  elements  seem  to  divide  in  their  middle, 
forming  a  clear  transverse  line  or  segment,  called  the  line  of 
Hensen  ;  while  the  ends  of  the  elements  approach  the  ends  of 
the  corresponding  elements  of  the  adjacent  discs,  and  tend  to 
obliterate  the  clear  segment  between.  Thus,  in  contracted 
muscle  the  light  and  the  dark  stria3  seem  to  occupy  positions 
precisely  reverse  to  those  of  relaxed  muscle.  The  mechanism 
of  muscular  contraction  is  not,  however,  well  made  out. 

Cardiac  muscle :  The  muscular  substance  of  the  heart  has 
an  individual  character  of  its  own  (Fig.  29).  The  individual 
cells,  much  shorter  than  those  of  the  striated  variety,  are 
cylindrical  in  shape  with  square  or  serrated  ends;  they  send 
off  branches  which  unite  with  neighboring  cells.  Adjoining 
cells  meet  end  to  end,  the.  ends  being  so  closely  cemented 
together  that  the  points  of  junction  cannot  be  detected  with- 


Striated   muscle-cells   in 
section  (Klein). 


INVOLUNTARY  OR  NON-STRIATED  MUSCLE.          63 


FIG.  30. 


out  special  preparation  of  the  specimen.  Laterally  the  cells 
are  not  closely  crowded,  but  are  separated 
by  slight  intervals  filled  with  delicate  con- 
nective tissue  and  vascular  channels.  The 
cells  have  no  separable  sarcolemma.  Each 
cell  has  a  single  nucleus,  situated  in  the 
centre  of  its  protoplasm.  The  cells  are 
somewhat  striated  both  longitudinally  and 
transversely. 

Involuntary  or  non- striated  muscle  (Fig.  30) 
is  widely  distributed  throughout  the  viscera, 
being  found  in  especial  abundance  in  the 
alimentary  canal,  bloodvessels,  bladder,  and 
uterus.  Its  movements  are  not  under  the 
control  of  the  will,  but  are  of  an  automatic 
nature  and  are  more  slow  and  continuous 
than  those  of  the  voluntary  muscles. 

Involuntary,  non-striped,  or  smooth  mus- 

Fio.  29. 


Cardiac  muscle  (Dunham),  a.  nucleus ; 
6,  c,  cytoplasm ;  d,  cement  at  junction 
of  cells;  e,  areolar  or  "interstitial" 
tissue  between  the  cells ;  /,  capillary. 


Involuntary  muscle- 
cell  (Schafer.)  The 
nucleus  is  not  repre- 
sented sufficiently 
long. 


cle-cells  are  slender  and  fusiform  in  shape,  each  with  a  single 


64  THE  TISSUES. 

characteristic  elongated  or  rod  shaped  nucleus  in  its  centre. 
The  cells  have  a  parallel  and  overlapping  arrangement,  held 
together  by  a  scanty  cement-substance,  and  form  sheets,  rings, 
or  tubes  of  muscle.  Indistinct  longitudinal  and  transverse 
markings  are  sometimes  observed,  the  latter  being  probably 
folds  in  the  cell-walls.  The  cells  have  an  envelope  but  no 
separable  sarcolemma.  Some  authorities  describe  involuntary 
muscle-cells  as  having  longitudinal  ridges,  or  "  intercellular 
bridges,"  on  their  surface,  which  unite  with  the  ridges  of  the 
adjacent  cells. 

Nerve -tissue. 

The  elements  of  the  nervous  structures  are  greatly  extended 
cells,  called  neurons,  which  for  practical  convenience  may  be 
divided  into  nerve-cells,  nerve-fibres,  and  nerve-terminals. 
Their  description  will  be  deferred  to  that  of  the  nervous 
system  in  general. 

Free  Cells  and  Body-fluids. 

The  tissues  considered  hitherto  are  all  fixed.  The  present 
class  is  a  somewhat  miscellaneous  assemblage  of  those  body- 
elements  that  are  not  fixed,  but  free  or  fluid. 

They  may  be  grouped  as  follows  :  1 .  Unattached  cells,  free 
in  the  solid  tissues.  2.  Cellular  fluids — that  is,  fluids  in 
which  free  living  cells  are  suspended,  as  the  blood.  3.  Simple 
homogeneous  fluids,  mainly  secretions.  4.  Emulsions. 

The  free  cells,  situated  for  the  most  part  in  the  solid  tissues, 
but  not  attached  to  them,  are  represented  mainly  by  the 
wandering  cells,  the  lymphoid  cells  of  lymphoid  tissue,  and 
ova.  The  so-called  wandering  cells  are  leukocytes  or  lymph- 
corpuscles  which  have  escaped  from  the  bloodvessels  or 
lymphatic  structures  and  exist  free  and  migratory,  especially 
among  the  meshes  of  the  opener  or  areolar  forms  of  connec- 
tive tissue.  The  small  spherical  lymphoid  cells,  with  large 
prominent  nuclei,  which  occur  crowded  in  the  meshes  of 
retiform  or  lymphoid  tissue,  are  very  similar  to  and  closely 
related  to  the  corpuscles  of  lymph.  Some  of  the  cellular 
elements  of  bone-marrow  might  also  perhaps  be  included  in 
this  group.  The  ova  of  the  lower  animals  are  free  cells  ;  and 


SIMPLE  OR  HOMOGENOUS  FLUIDS.  65 

in  mammals  they  are  free  from  their  departure  from  the  ovary 
until  their  attachment  to  the  uterus,  and  even  afterward  they 
are  in  a  sense  independent. 

The  cellular  fluids  of  the  body  are  the  blood,  lymph,  and 
semen.  They  consist  of  actively  vital  cells  free  in  a  fluid 
matrix.  They  can  be  regarded  as  liquid  tissues  analogous  in 
all  respects  to  the  solid  tissues,  being  composed  of  cells  and 
an  abundant  intercellular  substance,  which  in  this  case  is  fluid. 
The  latter  differs  from  the  matrix  of  the  solid  tissues,  how- 
ever, in  that  it  is  not  produced  by  the  vital  activities  of  the 
cells  suspended  in  it. 

The  blood  consists  of  cells  or  corpuscles  of  three  kinds,  red 
corpuscles,  white  corpuscles  or  leukocytes  (of  which  there  are 
several  varieties),  and  blood-plates. 

Lymph  consists  of  a  fluid  portion,  or  serum,  containing 
lymph-corpuscles,  which  are  similar  to  or  identical  with  some 
forms  of  leukocytes.  Leukocytes  and  lymph-corpuscles  often 
find  their  way  into  the  fixed  tissues  or  on  mucous  surfaces. 

Semen  is  a  thick  opaque  fluid  containing  large  numbers  of 
spermatozoa,  together  with  some  loosened  cells  and  granules. 

The  simple  or  homogeneous  fluids  are  mainly  the  secretions  of 
the  various  glands,  consisting  usually  of  clear,  transparent  solu- 
tions without  any  proper  cellular  or  formed  elements.  Under 
the  microscope  they  exhibit  no  structural  features,  and  the 
study  of  their  composition  is  a  matter  for  chemical  or  micro- 
chemical  methods.  Among  them  may  be  mentioned  the  urine, 
perspiration,  saliva,  bile,  gastric  juice,  etc. ;  also  the  fluids 
moistening  the  mucous  surfaces,  of  which  mucus  is  a  promi- 
nent constituent. 

Although  these  fluids  contain  no  cellular  elements  as  proper 
or  essential  ingredients,  yet  they  sometimes,  notably  the  saliva 
and  urine,  contain  a  few  adventitious  cells  derived  from  the 
mucous  membrane  lining  the  surface  of  the  cavities  where 
they  occur.  The  chief  cells  thus  found  are  leukocytes  or 
lymph-cells  (as  the  "salivary  corpuscles")  which  have  worked 
their  way  through  the  mucous  membrane  to  the  surface ;  also 
ordinary  epithelium-cells  cast  off  from  the  epithelial  covering  ; 
and  "mucous  corpuscles,"  or  "  mueocytes,"  young  germinal 
epithelium-cells  from  the  lower  epithelial  layers  (especially  in 
the  bladder)  which  have  grown  rapidly  and  been  thrown  off 

5— Hist. 


66  THE  TISSUES. 

prematurely  as  free  spherical  corpuscles,  usually  larger  than 
leukocytes. 

Emulsions :  Milk  and  chyle  are  emulsions,  as  are  also  the 
yolk  of  birds'  eggs  and  the  milky  juice  of  certain  plants.  By 
means  of  certain  substances,  as  albumin,  oil  may  be  caused  to 
form  a  permanent  mixture,  or  emulsion,  with  water.  The  oil 
forms  minute  spherules  or  granules  enveloped  in  a  viscid  sub- 
stance, which  causes  them  to  retain  their  shape,  and  suspended 
in  the  watery  vehicle.  Milk  and  chyle  contain  large  numbers 
of  such  fat-granules,  which  are  very  minute  and  are  sus- 
pended in  an  abundant  aqueous  fluid.  Their  opacity  and 
whiteness  are  due  to  the  reflection  of  the  rays  of  light  from 
the  granules.  In  artificial  emulsions  the  spherules  of  fat  are 
much  coarser  and  the  proportion  of  water  that  can  be  intro- 
duced far  less  than  is  the  case  with  these  natural  emulsions. 


CHAPTER    V. 
GLANDS;  MUCOUS  AND  SEROUS   MEMBRANES;  ORGANS. 

BEFORE  beginning  the  consideration  of  the  organs  and  sys- 
tems in  detail,  it  will  be  convenient  to  consider  briefly  :  (1) 
certain  composite  structures  of  wide  distribution,  namely, 
glands,  mucous  membranes,  and  serous  membranes ;  and  (2) 
organs  in  general. 

Glands  are  of  two  entirely  distinct  types  :  (a)  lymphoid  and 
blood-glands ;  and  (6)  secretory  or  epithelial  glands. 

The  lymphoid  glands,  as  the  lymphatic  glands,  thymus, 
tonsils,  and  lymphoid  tissue  generally,  consist  of  an  open  net- 
work of  retiform  tissue  the  meshes  of  which  are  filled  with 
lymph-corpuscles  and  lymph.  The  lymph-stream  passes 
directly  through  them.  They  have  no  proper  secretion, 
possess  no  outlet-ducts,  and  communicate  only  with  lymphatic 
vessels.  Their  function  is  not  completely  understood,  but 
they  partly  serve  to  develop  some  of  the  corpuscular  elements 
of  the  blood  and  lymph,  and  partly  to  arrest  noxious  sub- 
stances in  the  circulation. 

The  blood-glands,  as  the  spleen,  bear  the  same  relation  to  the 
blood-stream  that  the  lymphoid  glands  do  to  the  lymph- 
stream.  In  general  structure  they  resemble  the  lymphoid 
glands. 

The  secretory  glands  remove  or  secrete  from  the  blood 
various  substances  and  fluids  needed  for  special  purposes. 
The  active  agent  in  this  process  is  the  glandular  epithelium, 
which  forms  a  layer  supported  on  a  basement-membrane ; 
beneath  and  in  close  relation  with  the  epithelium  is  a  rich 
capillary  blood-supply ;  on  the  free  surface  of  the  epithelium 
is  an  open  space  or  cavity  in  which  the  secreted  product  col- 
lects and  is  carried  away.  Such  is  the  general  structure  of 
all  secretory  glands :  a  sac  of  epithelium  with  blood-supply 
on  the  outside  and  a  collecting  cavity  inside.  The  epithelium 

67 


68       GLANDS;  MUCOUS  AND  SEROUS  MEMBRANES. 

of  the  secreting  portion  of  glands  is  usually  different  from 
that  of  the  ducts. 

Secretory  glands  are  of  two  kinds :  closed  or  ductless  glands  ; 
and  the  ordinary  open  glands  with  ducts. 

The  secretory  ductless  glands  are  the  thyroid,  parathyroids, 
adrenals,  pituitary  body,  and  pineal  body.  They  have  no 
outlets  nor  ducts,  and  hence  their  secretions  are  not  discharged 
elsewhere  except  by  reabsorption  into  the  blood  or  lymph  cir- 
culation. The  lymphoid  and  blood-glands  are  also  "  duct- 
less." 

The  open  glands  are  the  ordinary  variety,  as  the  kidney, 
salivary  glands,  pancreas,  with  outlet-ducts  through  which 
their  secretions  are  discharged. 

In  addition  to  these  secreting  bodies,  certain  endothelial 
structures  may  be  mentioned,  as  bursse,  synovial  sacs,  etc., 
which  contain  glairy  lubricating  fluids  produced  by  the 
endothelium  also  by  a  true  secretory  process. 

Internal  and  external  secretions  :  The  purpose  and  mechan- 
ism of  the  ductless  glands,  closed  as  they  are,  have  long  been 
obscure,  but  recent  theories  afford  some  explanation  of  the 
subject.  According  to  these  theories,  the  secretions  elaborated 
by  glands  are  of  two  kinds,  internal  and  external. 

The  external  secretions  are  those  of  the  ordinary  kind,  dis- 
charged through  the  ducts  of  the  glands  and  conveyed  to  the 
places  where  their  functions  are  carried  out,  as  the  tears,  the 
bile ;  their  action  is  easily  comprehensible. 

The  internal  secretion,  however,  is  not  discharged  by  gland- 
ducts,  but  is  absorbed  into  the  circulation  and  there  serves 
purposes  useful  in  the  animal  economy.  This  is  the  only 
kind  of  secretory  activity  which  the  ductless  glands  manifest. 
The  secretion  of  the  thyroid,  for  instance,  when  in  the  blood, 
increases  oxidation,  promoting  metabolism,  and  increasing  the 
rapidity  of  cell-life  ;  stimulates  cerebral  activity,  makes  the 
heart  action  more  rapid,  causes  palpitation,  and  dilates  the 
bloodvessels.  That  of  the  suprarenals  is  a  powerful  vaso- 
motor  constrictor  and  probably  serves  to  maintain  vascular 
tone. 

The  effects  of  these  internal  secretions  are  most  markedly 
manifested  when  they  are  absent  from  the  blood,  as  when  the 
glands  producing  them  are  removed  or  impaired  by  disease ; 


INTERNAL  AND  EXTERNAL  SECRETIONS. 


69 


thus,  removal  or  impairment  of  the  thyroid  causes  myxoedema  ; 
of  the  suprarenals,  Addison's  disease  ;  of  the  pituitary  body, 
acromegaly.  It  would  seem  as  if  the  presence  of  the  internal 
secretions  in  the  blood  afforded  stimuli  necessary  to  preserve 


FIG.  31. 


FIG.  32. 


Simple  tubular  gland. 
FIG.  33. 


Compound  tubular  gland. 
FIG.  34. 


saccular  gland. 
Morphologic  types  of  secretory  glands    (Dunham). 


Compound  or  racemose  saccular 
gland. 


a  certain  tonus  and  produce  definite  reactions  of  the  bodily 
cells. 

Some  of  the  glands  with  ducts,  moreover,  seem  to  produce 


70       GLANDS,-   MUCOUS  AND  SEROUS  MEMBRANES. 

internal  as  well  as  external  secretions.  Thus,  the  glycogenic 
and  urea-forming  functions  of  the  liver  and  the  relation  of  the 
pancreas  to  glycosuria  are  instances  of  internal  secretory  action. 
Morphology  of  secretory  glands  (Figs.  31-34) :  The  secret- 
ing glands,  according  to  their  form,  are  divisible  into  two 
classes:  tubular  and  saccular ;  each  of  these,  again,  may  be 
simple  or  compound. 

Simple  tubular  glands  consist  of  single  tubes  lined  with 
epithelium,  with  one  end  closed  and  blind  and  the  other 
opening  on  the  skin  or  mucous  surface.  The  glands  of 
Lieberkiihn  and  some  of  the  gastric  and  uterine  glands  are 
typical  examples ;  the  sweat-glands  are  single  tubes,  modified 
in  having  the  secreting  portion  much  coiled. 

In  compound  tubular  glands  the  tubular  structure  is  still 
present,  but  the  tubes  branch  and  divide,  discharging  into  a 
common  duct.  Some  of  the  gastric  and  uterine  glands 
exhibit  the  simplest  gradations  into  this  type.  The  kidneys, 
testicles,  and  liver  are  compound  tubular  glands. 

Simple  saccular  glands  consist  of  a  single  rounded  or 
spherical  cavity  or  glandular  sac  with  a  small  outlet  to  the 
surface.  Some  of  the  simplest  sebaceous  glands  may  be  of 
this  type,  but  they  scarcely  occur  otherwise  in  mammals. 

Compound  saccular  or  racemose  glands,  as  the  salivary, 
mucous,  lachrymal,  sebaceous,  and  mammary  glands,  consist 
of  numbers  of  saccules  opening  into  common  ducts,  and  these 
again  uniting  in  larger  ducts,  much  like  a  bunch  of  grapes. 
In  compound  glands  the  ultimate  saccules  or  alveoli  which 
communicate  with  common  ducts  form  well-marked  groups, 
so  that  a  division  of  the  gland  into  lobes  and  lobules  is  easily 
recognizable.  The  lobular  divisions  of  glands  are  usually 
separated  by  distinct  partitions  of  connective  tissue,  inter- 
lobular^  septa.  Well-marked  divisions  of  the  ducts  are  also 
recognizable,  corresponding  to  their  degree  of  division  and  to 
their  situation  and  relation  to  the  lobules.  Within  a  lobule  is 
a  small  division  of  the  ducts,  the.  intralobulur  dud,  into  which 
the  ultimate  alveoli  of  that  lobule  all  empty.  The  short  duct 
by  which  each  individual  saccule  or  alveolus  empties  into  the 
intralobular  duct  is  called  an  intermediate  duct;  the  union  of 
the  intermediate  ducts  forms  the  intralobular  ducts.  The 
intralobular  ducts  unite  to  form  the  interlobular  ducts,  which 


MUCOUS  GLANDS. 


71 


are  larger  and  lie  in  the  connective  tissue  separating  the 
lobules.  By  the  union  of  the  interlobular  ducts  the  large 
common  duet  or  ducts  of  the  whole  gland  are  formed. 

According  to  the  nature  of  their  secretion  and  corresponding 
characteristics  of  the  gland-cells,  most  secretory  glands  are 
divisible    into    serous     glands,    mucous 
FIG.  35.  glands,  and  fatty  glands. 

Serous  glands  (Fig.  35),  as  the  parotid 
and  pancreas,  secrete  limpid  watery  fluids 
or  solutions.  The  secreting-cells  are 
spheroidal  or  polyhedral,  granular,  dark 
and  opaque,  stain  deeply,  and  have  rounded 
nuclei  nearly  centrally  located.  The  ap- 

Alveolusof  serous  gland  J 

(Schieflerdecker).  pearance  ot  the  cells  varies  somewhat 
according  to  the  stage  of  secretion.  When, 
after  resting  for  a  time,  they  are  charged  with  secretion,  they 
are  distended,  clearer,  less  opaque,  stain  less  deeply,  and  contain 
an  abundance  of  granules.  After  being  exhausted  by  pro- 
longed secretion  they  are  shrunken  or  diminished  in  size  ; 
darker,  more  opaque,  and  more  deeply 
stained  (from  condensation  of  the  pro- 
toplasm) ;  and  less  granular,  having 
discharged  their  granular  contents  into 
the  lumen  of  the  gland. 

Mucous  glands  (Fig.  36),  as  the  sub- 
lingual,  secrete  a  viscid,  mucinous 
fluid,  wrhich  lubricates  the  mucous  sur- 
faces. Goblet  epithelium-cells  secrete 
a  similar  substance,  and  the  character-  Alveolus 
istics  of  these  cells  are  very  similar 
to  those  of  the  cells  of  mucous  glands.  Small  racemose 
mucous  glands  are  widely  distributed  in  mucous  membranes, 
having  their  alveoli  in  the  submucosa  and  their  ducts  opening 
on  the  surface.  The  secreting-cells  of  mucous  glands,  when 
in  the  resting  stage  and  distended  with  their  mucinous  secre- 
tion, are  large  and  swollen,  unstained,  clear,  and  transparent, 
especially  in  the  superficial  portion  ;  their  nuclei  and  body- 
protoplasm  are  crowded  well  toward  the  bases  of  the  cells. 
When  exhausted  by  continued  activity  they  are  smaller,  less 
clear,  and  more  granular  in  appearance. 


FIG.  36. 


0m  KP°US  gland' 


72       GLANDS;  MUCOUS  AND  SEROUS  MEMBRANES. 

Fatty  glands  :  The  sebaceous  and  mammary  glands  produce 
the  fatty  constituents  of  their  secretions  by  a  fatty  degenera- 
tion or  infiltration  of  the  protoplasm  of  the  gland-cells.  The 
cell-bodies  become  swollen  and  infiltrated  with  globules  of 
fat,  which  are  later  discharged  into  the  lumen. 

Mucous  membranes :  The  mucous  membranes  are  those 
lining  the  spaces  within  the  body  that  communicate  directly  or 
indirectly  with  the  exterior.  There  are  three  distinct  continu- 
ous tracts  of  mucous  membrane  :  the  respiratory-alimentary, 
the  genito-urinary,  and  the  mammary.  At  the  orifices  and 
along  portions  of  these  tracts  the  mucous  membrane  is  a  con- 
tinuation of  and  similar  in  structure  to  the  skin.  In  some  situ- 
ations the  function  of  mucous  membrane,  like  that  of  the  skin,  is 
chiefly  protective,  and  in  these  places  it  most  resembles  the 
skin.  In  other  situations  mucous  membrane  has  special 
functions,  and  its  structure  varies  accordingly. 

Mucous  membrane  is  usually  described  as  being,  in  general, 
composed  of  two  layers,  the  mucosa  and  the  submucosa, 
which  are  commonly  situated  on  a  muscular  or  fibrous  bed. 

The  mucosa  consists  of :  (a)  a  superficial  layer  of  epithelium, 
stratified  squamous,  columnar,  or  ciliated,  corresponding  to 
the  epidermis  of  the  skin.  Beneath  the  epithelium  is  (6)  the 
tunica  propria,  a  layer  of  connective  tissue,  white-fibrous  or 
elastic,  corresponding  in  general  to  the  corium  of  the  skin,  but 
varying  greatly  in  different  situations.  Its  upper  or  outer 
surface  is  condensed  to  form  a  basement-membrane  for  the 
support  of  the  overlying  epithelium.  Beneath  the  tunica 
propria  in  many  places  is  (c)  the  muscularis  mucosce,  a  thin 
sheet  of  involuntary  muscle-cells,  some  longitudinally  arranged, 
some  transverse  ;  it  separates  the  mucosa  from  the  submucosa, 
and  has  no  analogue  in  the  skin. 

The  submucosa  is  a  layer  of  areolar  tissue  underneath  the 
mucosa,  corresponding  to  the  areolar  subcutaneous  tissue  ;  it 
contains  the  larger  vascular,  lymphatic,  and  nerve  branches, 
which  send  smaller  twigs  and  capillaries  into  the  tunica 
propria.  The  looseness  of  the  subrtiucosa  permits  some  play 
or  movement  of  the  mucous  layer  on  the  layers  beneath. 
Lymphoid  tissue,  diffuse  or  circumscribed,  is  present  in  many 
situations  in  the  submucosa  or  tunica  propria. 


SEROUS  MEMBRANES.  73 

Secretion :  Mucous  membranes  are  bathed  and  lubricated 
in  a  mucinous  fluid,  secreted  mostly  by  goblet-cells  or  special 
small  mucous  glands.  Most  mucous  membranes  lined  with 
stratified  squamous  or  stratified  ciliated  epithelium  are  pro- 
vided with  large  numbers  of  mucous  glands ;  in  the  stomach 
and  intestines  (lined  by  simple  columnar  epithelium)  mucus 
is  secreted  by  large  numbers  of  goblet-cells,  no  mucous  glands 
being  present.  Some  mucous  membranes  lined  with  stratified 
squamous  epithelium,  however,  lack  both  goblet-cells  and 
mucous  glands,  as  in  the  vagina  and  bladder,  whose  mucous 
secretion  is  ^produced  by  the.  mucinogenous  action  of  the 
squamous  cells  themselves.  The  mucous  glands  when  present 
have  their  alveoli  in  the  submucosa  and  their  ducts  penetrate 
the  mucosa  to  empty  on  the  surface ;  the  cells  of  the  secreting 
portions  of  these  glands  are  of  the  mucous  glandular  type, 
while  the  ducts  are  lined  with  a  different  form  of  cell,  usually 
cuboidal  or  columnar  cells  similar  to  or  merging  into  those  of 
the  epithelial  surface. 

These  are  the  general  features  of  the  structure  of  mucous 
membranes,  but  the  details  vary  greatly  in  different  situations. 

Serous  membranes,  as  the  pleura,  pericardium,  peritoneum, 
tunica  vaginalis,  and  the  allied  synovial  membranes,  line 
certain  closed  cavities  or  sacs.  The  portion  of  serous  mem- 
branes covering  the  viscera  is  called  the  visceral  portion,  that 
reflected  over  the  outer  walls  of  the  cavity  being  the  parietal 
portion.  Serous  membranes  consist  of  an  interlacing  fibrous 
connective-tissue  membrane  or  basis,  lined  on  the  free  surface 
by  endothelium,  while  beneath  is  a  variable  amount  of  areolar 
and  often  adipose  tissue,  the  subserous  tissue,  connected  with 
the  subjacent  structures  and  analogous  to  the  submucosa. 
They  contain  blood  and  lymphatic  vessels.  Between  the 
endothelium-cells  in  some  localities  are  occasional  minute 
orifices  or  lymph-stomata,  guarded  by  small  spheroidal  cells ; 
these  open  into  lymphatic  vessels  within  the  membrane.  Thus 
the  serous  sacs  form  large  lymph-spaces,  communicatingdirectly 
with  the  lymphatic  channels.  The  function  of  serous  mem- 
branes is  partly  associated  with  that  of  the  lymphatic  system, 
and  is  largely  to  obviate  friction  and  to  permit  and  facilitate 
the  gliding  movement  of  viscera  upon  opposing  surfaces. 


74       GLANDS;  MUCOUS  AND  SEROUS  MEMBRANES. 

Organs  are  aggregations  of  the  elementary  cells  and  tissues 
in  varying  proportions  and  varying  modes  of  arrangement. 
The  tissues  of  many  organs  can  be  conveniently  divided  into 
parenchymatous  tissue  and  sustentacular  tissue. 

The  parenchyma  of  organs  consists  of  the  cells  or  portions 
that  are  the  active  and  essential  agents  in  carrying  on  the 
functions  of  the  organ,  such  as  the  glandular  epithelium  of 
glands,  the  air-vesicles  of  the  lungs,  etc.  The  sustentacular 
tissue  (often  called  interstitial  tissue)  of  organs  consists  of 
their  connective-tissue  framework,  permeating  and  supporting 
all  their  parts.  It  is  usually  a  fibro-elastic  or  condensed 
areolar  tissue.  Different  parts  or  divisions  of  the  sustentacu- 
lar tissue  can  often  be  distinguished,  such  as  the  membranous 
envelopes  or  capsules  surrounding  organs;  trabeculie  or  septa 
(interlobular  tissue)  traversing  the  interior  of  organs  and 
dividing  them  into  lobes  and  lobules ;  tracts  of  fibrous  tissue 
(perivascular  tissue,  etc.)  surrounding  and  supporting  the 
vascular  and  nerve  branches,  and  ducts,  in  their  ramifications 
through  the  organ  ;  and  a  delicate  all-pervading  network  of 
fibrous  tissue  (intralobular  tissue)  embracing  and  sustaining 
the  minutest  subdivisions  of  the  visceral  and  parenchymatous 
substance.  In  addition  to  their  sustentacular  and  parenchy- 
matous elements  organs  possess  as  a  matter  of  course  a  blood, 
lymphatic,  and  nerve  supply. 


CHAPTER   YL 
THE  CIRCULATORY  SYSTEM. 

THE  apparatus  by  which  the  circulation  of  the  blood 
throughout  the  body  for  the  nourishment  of  the  tissues  is 
accomplished  consists  of  the  heart,  covered  by  the  pericar- 
dium ;  and  the  bloodvessels :  arteries,  veins,  and  capillaries. 

The  heart  is  a  hollow  muscular  organ,  whose  walls  are  made 
up  of  a  thick  mass  of  muscle,  the  myocardium,  lined  on  the 
inside  by  a  delicate  endothelial  membrane,  the  endocardium  ; 
and  on  the  outside  by  a  serous  membrane,  the  visceral  portion 
of  the  pericardium. 

The  endocardium,  which  lines  the  interior  of  the  heart,  is 
similar  to  the  lining  of  the  bloodvessels,  of  which  it  is  a 
continuation.  It  is  thinner  than  the  pericardium.  Its  free 
surface  is  lined  by  polygonal  endothelium-cells,  which  lie  on 
a  firm  connective-tissue  basis  of  interlacing  white  and  elastic 
fibres.  The  lowermost  tissue  of  the  endocardium  merges 
gradually  into  the  delicate  connective  tissue  which  occupies 
the  interstices  between  the  muscle-cells  of  the  myocardium. 

The  valves  of  the  heart  and  arterial  orifices  consist  of  folds 
or  reduplications  of  the  endocardium,  fortified  and  strength- 
ened by  additional  white  and  elastic  fibrous  tissue.  The  tis- 
sues at  the  bases  of  the  valves  are  strengthened  into  well- 
marked  fibrous  rings,  which  serve  as  a  basis  for  the  attach- 
ment or  insertion  of  the  valves  and  muscular  bundles  of  the 
myocardium. 

The  myocardium  is  a  muscular  mass  making  up  the  main 
substance  of  the  heart.  The  cardiac  muscle-cells  of  which  it 
is  composed  are  of  a  kind  peculiar  to  the  heart,  and  have  been 
already  described  (Fig.  29).  The  muscular  fibres  are  arranged 
in  bundles  or  layers  which  in  different  places  run  in  different 
directions,  transverse,  longitudinal,  oblique,  spiral,  in  an  intri- 
cate manner. 

75 


76 


THE  CIRCULATORY  SYSTEM. 


Cardiac  muscle-tissue  is  not  compact,  but  the  sides  of  the 
muscle-cells  are  separated  by  slight  intervals  or  interstices 
through  which  delicate  connective  tissue  (the  interstitial  tissue), 
capillaries,  lymphatics,  and  nerves  permeate  the  entire  myo- 
cardium. The  blood-supply  of  the  heart,  including  the  endo- 
cardium and  visceral  pericardium,  is  derived  from  the  coronary 
vessels;  the  muscle-cells  are  richly  supplied  with  capillaries. 

The  pericardium  is  a  typical  serous  sac,  consisting  of  a  fibro- 
elastic  membrane  (fibrous  pericardium)  lined  on  the  free  interior 
surface  by  a  single  layer  of  polygonal  endotheli urn-cells  (serous 

FIG.  37. 


Cross-section  of  artery  (Dunham),    a,  endothelial  lining ;  6,  internal  elastic  lamina ; 
c,  tunica  media ;  d,  tunica  adventitia ;  e,  adipose  tissue ;  /,  small  nerve. 

pericardium) ;  beneath  which  is  the  subserous  or  subpericardial 
areolar  tissue,  which  in  this  situation  often  includes  masses  of 
fatty  tissue.  The  visceral  portion  of  the  serous  pericardium, 
sometimes  called  the  epicardium,  envelops  the  outside  of 
the  heart,  while  its  parietal  portion  is  reflected  on  and  lines 
the  inner  surface  of  the  fibrous  pericardium.  Under  the  portion 
of  the  pericardium  which  covers  the  heart  the  subpericardial 
tissue,  areolar  and  fatty,  is  continuous  with  and  merges  into 
the  interstitial  connective  tissue  of  the  myocardium. 


ARTERIES.  77 

Arteries  :  The  arteries  vary  in  structure  somewhat — that  is, 
in  the  relative  proportions  of  their  several  constituents — ac- 
cording to  their  size  and  degree  of  subdivision  (Fig.  37).  The 
coats  of  arteries  are  usually  described  as  consisting  of  three 
divisions,  the  tunica  intima,  tunica  media,  and  tunica  adven- 
titia.  The  structure  of  medium-sized  arteries,  or  all  but  the 
largest  and  the  smallest,  is  as  follows  : 

The  tunica  intima,  or  internal  coat,  consists  of  three  layers. 
It  is  lined  internally  by  endothelium,  a  single  layer  of  flat 
sqtiamous  cells  uniting  by  somewhat  sinuous  edges,  oval  and 
elongated  in  shape  and  with  oval  nuclei ;  the  cells  and  nuclei 
lie  with  their  long  axes  parallel  with  the  course  of  the 
artery.  These  cells  present  a  smooth  surface  to  the  blood- 
stream. 

Beneath  the  endothelium  is  the  subendothelial  connective 
tissue,  a  thin  delicate  layer  of  white  and  elastic  fibrous  tissue 
with  stellate  connective-tissue  cells.  In  the  smallest  arteries 
this  layer  becomes  thinner  and  finally  disappears. 

The  lowest  layer  of  the  tunica  intima,  separating  it  from 
the  tunica  media,  is  the  internal  elastic  lamina,  a  thin  but 
prominent  layer  of  interlacing  yellow  elastic  fibres  forming  a 
perforated  or  sometimes  almost  continuous  membrane ;  it  is 
sometimes  called  the  afenestrated  membrane  of  Henle."  In 
empty  and  contracted  arteries  this  elastic  lamina  is  thrown 
into  longitudinal  folds,  and  in  cross-sections  of  arteries  it  con- 
sequently presents  a  very  conspicuous  and  characteristic  ap- 
pearance as  a  clear  sinuous  yellow  line  surrounding  the  lumen 
of  the  vessel. 

The  tunica  media  is  a  thick  middle  coat,  between  the  intima 
and  adventitia,  consisting  chiefly  of  intermingled  yellow  elastic 
fibres  and  involuntary-muscle  cells,  along  with  a  small  amount 
of  white  fibres.  The  muscle-cells  are  for  the  most  part  ar- 
ranged circularly  or  transversely,  but  in  a  few  arteries  longi- 
tudinal cells  also  occur  sparingly.  The  elastic  tissue  occurs 
as  sinuous  fibres,  networks,  and  plates.  In  relative  quantity 
the  elastic  and  muscular  elements  vary  inversely  to  each  other 
according  to  the  size  of  the  artery. 

*  In  the  large  arteries  the  elastic  tissue  greatly  predominates 
in  amount  over  the  muscle ;  as  the  arteries  decrease  in  size 
these  proportions  are  gradually  reversed,  until  in  the  small 


78  THE  CIRCULATORY  SYSTEM. 

arteries  the  media  is  mainly  composed  of  muscle-cells,  with 
elastic  tissue  only  scantily  represented. 

This  arrangement  confers  great  elasticity  on  the  largest 
arteries,  so  that  they  convert  the  spurts  of  blood  intermittently 
pumped  from  the  heart  into  a  more  even  and  continuous  cur- 
rent ;  while  the  smaller  arteries,  by  the  action  of  the  vaso-con- 
strictor  and  vaso-dilator  nerves  upon  their  muscular  walls  and 
their  calibre,  are  kept  well  under  the  control  of  the  nervous 
system,  which  in  this  way  exercises  a  full  and  highly  coordi- 
nated control  over  the  circulation  and  amount  of  blood-supply 
in  all  parts  of  the  body. 

In  some  arteries  an  external  elastic  lamina,  similar  to  but 
less  well  marked  than  the  internal  elastic  membrane,  can  be 
distinguished,  marking  the  outer  limit  of  the  tunica  media  and 
separating  it  from  the  tunica  adventitia. 

The  tunica  adventitia,  the  outer  coat  of  the  arterial  wall,  is 
a  layer  of  fibrous  and  elastic  tissue,  containing  perivascular 
lymphatics  and  the  vasa  and  nervi  vasorum,  or  the  small 
bloodvessels  and  nerve-filaments  that  supply  the  walls  of  the 
artery  itself.  The  adventitia  is  of  indefinite  and  variable 
thickness  in  different  situations ;  the  portion  next  to  the 
media  is  a  firm,  strong  tissue,  while  the  more  remote  portions 
become  looser  and  more  areolar  and  merge  gradually  into  the 
neighboring  connective  tissues. 

In  the  largest  arteries,  as  the  aorta  and  pulmonary  artery, 
the  subendothelial  tissue  is  thick  and  firm,  and  the  internal 
elastic  lamina  is  ill  defined.  The  tunica  media  is  made  up 
mainly  of  elastic  plates  and  reticula,  the  muscle-cells  being 
present  in  relatively  small  proportion. 

As  the  arteries  decrease  in  size,  the  subendothelial  tissue  and 
the  elastic  elements  of  the  media  diminish  and  ultimately 
disappear,  the  muscle-cells  become  fewer  and  scattered,  the 
adventitia  decreases  in  amount,  and  the  internal  elastic  lamina 
becomes  thinner  and  finally  absent.  The  endothelium  persists 
throughout. 

The  smallest  terminal  arteries,  then,  are  lined  with  endo- 
thelium, resting  on  the  thin  remnants  of  the  subendothelial 
connective-tissue  and  elastic  layers;  outside  of  this  are  trans- 
verse involuntary  muscle-cells  in  a  single  layer  or  scat- 
tered and  separated  by  intervals  ;  and  surrounding  all  is 


VEINS.  79 

scanty  connective  tissue  representing  the  remains  of  the 
adventitia. 

In  small  arteries,  viewed  longitudinally  (or  from  the  side), 
the  transverse  muscle-cells,  with  their  conspicuous  rod-shaped 
nuclei,  present  a  very  characteristic  appearance  by  which 
vessels  of  this  size  are  easily  recognized. 

When,  finally,  all  the  coats  have  disappeared  except  the 
endothelium,  the  artery  has  merged  into  a  capillary. 

Veins  :  The  structure  of  veins  is  much  the  same  as  that  of 
arteries ;  but  they  have  a  larger  calibre,  thinner  walls,  more 
white  fibrous  tissue,  and  less  muscle  than  the  corresponding 
arteries,  and  they  are  provided  with  valves. 

The  walls  of  veins,  as  of  arteries,  consist  of  three  coats, 
the  tunica  intima,  tunica  media,  and  tunica  adventitia. 
These  coats,  however,  are  often  indistinctly  marked  off 
and  merge  into  one  another  without  well-marked  dividing- 
lines. 

The  tunica  intima  is  lined  internally  with  a  single  layer  of 
endothelium-cells,  which  are  more  polygonal  and  less  elongated 
in  shape  than  are  those  of  arteries.  The  subendothelial  layer 
consists  of  white  and  elastic  tissue.  The  internal  elastic 
lamina  in  veins  is  often  poorly  defined. 

The  tunica  media  consists  of  white  and  elastic  fibrous  tissue 
and  involuntary  muscle-cells,  which  are  mostly  arranged 
circularly,  but  in  some  situations  partly  longitudinally  also. 
The  media  is  much  thinner  and  contains  less  muscle  than  in 
arteries. 

The  tunica  adventitia  is  a  fibro-elastic  outer  sheath,  often 
thick  and  well  marked,  containing  vasa  vasorum  and  in  some 
situations  longitudinal  non-striated  muscle-cells. 

The  valves  of  veins  are  folds  of  the  tunica  intima,  strength- 
ened bv  additional  connective  tissue. 

At  the  junction  of  the  large  rein*  with  the  cardiac  auricles 
the  peculiar  muscle  of  the  heart  is  continued  for  a  short  dis- 
tance in  the  venous  walls.  The  walls  of  the  veins  of  the 
lower  extremities  are  thicker  and  more  muscular  than  those  of 
the  upper  part  of  the  body. 

The  venous  N/////.NVX  of  the  interior  of  the  skull  consist 
of  an  endothelial  layer  resting  on  fibrous  tissue,  and  occupy 


80  THE  CIRCULATORY  SYSTEM. 

spaces   formed    by    separation    of    the   layers   of    the    dura 
mater. 

Some  veins  are  devoid  of  muscle-tissue. 

Capillaries :  The  capillaries  are  minute  tubes  formed  of  a 
single  layer  of  elongated  flat  squamous  nucleated  endothelium- 
cells,  with  their  long  axes  arranged  longitudinal  to  the  course 
of  the  vessels.  They  are,  therefore,  continuations  of  the 
endothelial  linings  of  the  arteries  and  veins,  but  divested  of 
all  other  coverings,  except  that  whatever  traces  of  connective 
tissue  may  surround  the  endothelial  tubes  may  be  regarded  as 
vestiges  of  the  adventitia. 

At  the  junction  of  the  endothelial  cells  in  places  are  small 
points,  which  are  perhaps  stomata  or  openings,  by  which  the 
escape  or  migration  of  leukocytes  through  the  wall  of  the  capil- 
lary is  effected  or  facilitated. 

The  capillaries  form  a  system  of  exceedingly  numerous  short 
minute  passages  connecting  the  terminal  arteries  on  the  one 
side  with  the  initial  veins  on  the  other.  They  branch  and 
anastomose  so  as  to  form  reticula  or  networks,  varying  in  the 
closeness,  form,  and  arrangement  of  the  meshes  in  different 
organs  and  situations,  according  to  the  blood  supply  locally 
required.  The  capillaries  lie  in  intimate  relation  with  all  the 
tissues,  and  nearly  all  parts  of  the  body  are  closely  permeated 
by  these  channels.  From  the  capillaries  the  blood  accom- 
plishes its  metabolic  and  nutritional  action  on  the  body-tissues. 
The  capillaries  are  therefore  the  ultimate  active  functional 
elements  of  the  circulatory  system,  to  which  all  the  rest  of 
the  circulatory  apparatus  serves  a  subordinate  and  tributary 
purpose. 

The  thin  walls  of  the  capillaries  are  highly  endowed  with 
the  vital  properties  of  protoplasm,  and  are  well  fitted  for  the 
exosmosis  of  nutrient  fluids  ;  the  endosmosis  of  carbon  dioxide 
and  other  waste  products  of  tissue-katabolism  ;  and  the  passage 
of  leukocytes  through  them. 

Vascular  sinuses  :  In  some  situations  the  vascular  passages 
are  dilated  or  distended  in  the  form  of  cavernous  spaces  or 
sinuses  (often  called  venous  sinuses),  lined  with  endothelium 
and  communicating  with  arteries  and  veins,  and  with  one 


VASCULAR  SINUSES.  81 

another.  Such  sinuses  may  be  interposed  between  the  terminal 
arteries  and  the  commencing  veins,  taking  the  place  of  capil- 
laries, as  in  the  spleen  and  bone-marrow. 

The  erectile  tissue  of  the  male  and  female  genitals  consists 
of  similar  vascular  sinuses  so  arranged  that  when  the  exit  of 
the  blood  is  checked  by  muscular  compression  of  the  outlet- 
veins  the  spaces  are  distended  with  blood  and  the  organ  be- 
comes turgid  and  erect. 

6-   Hist. 


CHAPTER    VII. 
THE  LYMPHATIC  SYSTEM. 

Tx  the  main  the  lymphatic  system  consists  of  a  series  of  ves- 
sels or  channels  distributed  throughout  the  entire  organism  and 
serving  chiefly  for  draining  away  superfluous  fluids  in  the 
tissues  and  returning  them  into  the  blood. 

The  fluid  contained  in  these  channels  is  the  lymph. 

The  absorptive  action  of  the  lymphatics,  as  in  the  intestinal 
walls  and  the  removal  of  substances  introduced  hypodermi- 
cally,  is  allied  to  their  drainage  function.  In  some  situations, 
as  in  the  cornea  and  bone,  lymph-channels  afford  the  only 
passages  by  which  fluids  can  permeate  the  tissues  for  the 
purpose  of  nourishing  them. 

In  the  course  of  lymphatic  vessels  are  also  interposed  gland- 
ular structures,  which  among  other  functions  have  the  power 
of  arresting  noxious  and  toxic  bodies  in  the  lymphatic  circu- 
lation. 

The  morphologic  elements  of  the  lymphatic  system  may  be 
stated  to  be  lymph-spaces  and  origins,  lymphatic  vessels, 
lymphoid  tissue,  and  lymphatic  glands. 

Lymph-spaces  :  The  interstices  or  empty  spaces  in  tissues, 
especially  connective  tissues,  form  cavities  which  may  contain 
lymph  and  communicate  directly  or  indirectly  with  lymphatic 
vessels.  Cell-spaces,  the  intervals  between  (connective-tissue) 
cells  and  their  processes  and  the  walls  of  the  cavities  or 
lacunae  in  which  they  are  situated  (as  in  bone  and  the  cornea), 
often  afford  sufficient  room  for  the  passage  of  lymph.  In 
some  instances  separations  or  fissures  in  tissues  form  lymph- 
spaces,  without  any  specialization  of  the  walls;  in  other  cases 
the  walls  of  the  spaces  are  lined  partially  or  whollv  with 
flattened  connective-tissue  cells  or  endothelium.  The  lacunae 
and  canal iculi  of  bone,  the  cell-spaces  and  channels  in  the 
cornea,  the  minute  intervals  between  the  prickle-cells  of  the 
epidermis,  form  communicating  passages  by  which  lymph  can 


ORIGINS  OF  THE  LYMPHATIC  VESSELS.  83 

percolate  through  these  tissues,  which  are  not  supplied  by 
blood-capillaries,  and  afford  pabulum  for  their  nutrition  which 
would  otherwise  be  unprovided. 

Cell-spaces  are  also  especially  observable  in  the  fibrous 
tissue  of  the  central  tendon  of  the  diaphragm,  irregular  stellate 
lymph-spaces  corresponding  to  connective-tissue  cells,  with 
branches  communicating  with  one  another  and  perhaps  with 
lymph-vessels. 

The  spaces  in  areolar  tisane  also  serve  as  lymph-spaces, 
communicating  freely  with  the  lymph-vessels,  and  from  their 
looseness  are  capable  of  holding  large  accumulations  of  lymph 
and  fluid,  as  in  oedematous  conditions  and  subcutaneous  injec- 
tions. These  spaces  are  simply  fissures  in  the  substance  of 
the  connective  tissue,  without  any  specialized  walls. 

In  certain  regions,  notably  the  nervous  centres,  occur  well- 
marked  perivascular  and  perineurial  lymphatics,  consisting  of 
longitudinal  passages  or  clefts  in  the  tunica  adventitia  of  the 
bloodvessels  and  fibrous  tissue  surrounding  the  nerves ;  these 
passages  when  well  developed  may  be  lined  with  endo- 
thelium. 

The  open  meshes  of  lymphoid  tissue  also  constitute  lymph- 
spaces,  partially  lined  with  flat  connective-tissue  or  endo- 
thelioid  cells. 

The  serous  sacs,  as  the  pleura,  pericardium,  peritoneum, 
sy  no  vial  sacs,  bursse,  etc.,  may  be  regarded  as  representing 
highly  developed  lymph-spaces.  They  are  large  cavities 
completely  and  definitely  lined  by  serous  membranes,  which 
have  been  already  described  as  fibrous  membranes  lined  on 
the  free  surface  by  endothelium.  The  cavity  of  the  serous 
sacs  communicates  with  the  lymph- vessels  by  stomata.  The 
function  of  serous  membranes  is,  however,  apparently  more 
to  obviate  friction  and  facilitate  motion  between  opposing 
surfaces  than  to  serve  as  components  of  the  lymphatic  system. 
Ordinarily  the  serous  sacs  contain  only  a  small  amount  of 
fluid,  which  acts  as  a  lubricant ;  in  the  synovial  sacs  and 
bursse  this  fluid  is  much  different  from  ordinary  lymph,  being 
glairy  and  viscid  and  having  the  character  of  a  special  secre- 
tion. 

Origins  of  the  lymphatic  vessels:  The  lymph-spaces  just 
considered  constitute  the  chief  portion  of  the  ultimate  origins 


84  THE  LYMPHATIC  SYSTEM. 

of  the  lymph-vessels.  The  nutritive  fluids,  after  exuding 
from  the  blood-capillaries  and  bathing  the  tissues,  accumulate 
in  the  interstices  between  the  cells  and  in  the  spaces  in  the 
tissues.  These  spaces  open  directly  into  the  smallest  radicles 
or  capillaries  of  the  lymphatic  vessels ;  or  the  fluids  may 
enter  the  vessels  by  osmosis  through  their  thin  walls.  The 
lacteals  form  another  important  class  of  lymphatic  origins  ;  as 
elsewhere  described,  they  are  small  blind  tubes  occupying  the 
axis  of  the  villi  of  the  small  intestine,  and  emptying  into  the 
larger  lymphatic  vessels  in  the  submucosa.  They  are  really 
lymphatic  radicles  or  capillaries,  and  their  special  function  is 
to  absorb  into  the  circulation  the  fatty  and  other  food-mate- 
rials digested  and  elaborated  in  the  alimentary  canal.  The 
lymph-stomata,  minute  openings  guarded  by  small  spheroidal 
cells,  occurring  at  the  points  of  junction  of  the  endothelium- 
cells  of  serous  membranes,  also  form  a  sort  of  origin  or  open- 
ing into  lymph- vessels. 

Lymphatic  vessels :  The  lymph-vessels  form  a  series  of 
channels  ramifying  through  the  entire  body.  The  fluids  from 
the  lymph-spaces  and  lacteals  are  taken  up  by  the  small 
lymphatic  branches,  these  combine  to  form  larger  channels, 
and  finally  they  are  all  united  into  two  vessels,  the  thoracic 
duct  and  the  smaller  right  lymphatic  duct,  which  empty  into 
the  blood  at  the  junction  of  the  jugular  and  subclavian  veins 
on  each  side. 

The  smallest  lymphatic  vessels,  the  so-called  lymph-capil- 
laries, including  the  lacteals,  are  delicate  protoplasmic  tubes 
made  up  of  a  single  layer  of  polygonal  endothelium-cells. 
As  these  vessels  unite  and  become  somewhat  larger,  their 
endothelial  lining,  now  made  up  of  more  elongated  cells, 
becomes  surrounded  with  a  certain  amount  of  connective 
tissue.  The  smaller  lymphatic  channels  are  very  delicate, 
inconspicuous  structures  difficult  to  distinguish. 

The  larger  lymph- vessels  have  thicker  walls,  and  in  structure 
somewhat  resemble  the  veins.  Their  walls  are  composed  of 
three  coats.  The  inner  coat  is  lined  with  elongated  endothelium- 
cells,  beneath  which  is  a  thin  layer  of  connective  and  elastic  tis- 
sue. The  middle  coat  consists  mainly  of  elastic  tissue  and  in- 
voluntary muscle-cells  arranged  transversely.  The  external  coat, 
or  adventitia,  is  an  investment  of  fibrous  and  areolar  tissue. 


LYMPHOID   OR  ADENOID   TISSUE.  85 

Lymphatic  vessels  contain  numerous  valves,  formed  by 
transverse  folds  of  the  inner  tunic.  Associated  with  the  valves 
are  alternate  dilatations  and  constrictions  of  the  lymphatic 
vessels,  which  give  them  a  characteristic  beaded  appearance. 

The  thoracic  duct  is  the  largest  and  best  developed  of  the 
lymphatic  vessels.  Its  inner  tunic  contains  a  considerable 
amount  of  subendothelial  connective  tissue  and  longitudinally 
arranged  elastic  fibres.  Its  outer  coat  contains  scattered 
bundles  of  longitudinal  involuntary  muscle. 

Lymphoid  or  adenoid  tissue  consists  of  an  open  connective- 
tissue  network,  the  meshes  of  which  are  crowded  with  free 
cells,  called  lymphoid  cells,  the  whole  communicating  with 
lymphatic  vessels.  The  connective-tissue  reticulum  which 
forms  the  basis  of  typical  lymphoid  tissue  has  already  been 
described  under  the  name  retiform  tissue;  it  consists  of  fine 
interlacing  fibrils  covered  or  lined  at  their  intersections  with 
flat  stellate  connective-tissue  or  eudothelioid  cells.  The 
meshes  formed  by  this  structure  are  filled  with  lymphoid  cells, 
small  free  spherical  cells  with  relatively  large  and  prominent 
deeply  staining  round  nuclei  and  small  cell-bodies.  These  are 
ofteu  packed  in  so  densely  as  to  obscure  and  hide  the  reticular 
basis.  The  meshes  communicate  freely  with  one  another  and 
with  the  interior  of  entering  or  afferent  and  departing  or 
efferent  lymphatic  vessels,  so  that  the  tissue  forms  a  lymph- 
space,  and  through  it  lymph  constantly  flows.  Adenoid  tissue 
is  also  supplied  with  blood-capillaries. 

Lymphoid  tissue  exhibits  all  gradations  from  diffuse  masses 
without  definite  boundaries  to  sharply  circumscribed  nodules. 
Diffuse  lymphoid  tissue  occurs  imbedded  in  connective  tissue, 
and  merges  insensiblv  into  the  surrounding  tissues.  It  pre- 
sents all  grades  from  ordinary  connective  or  areolar  or  even 
epithelial  tissue  infiltrated  scantily  or  densely  with  wandering 
lymphoid  cells  to  typical  dense  adenoid  tissue  with  a  retiform 
basis. 

In  other  cases  lymphoid  tissue  forms  well-defined  nodules, 
more  or  less  spherical  in  shape,  often  quite  sharply  circum- 
scribed by  a  condensation  of  the  surrounding  fibrous  tissue. 
Such  nodules  are  often  called  lymph-follicles  (Fig.  38).  The 
afferent  lymph-vessels  are  said  to  open  into  the  periphery 
of  such  nodules  or  follicles.  The  tissue  in  the  centre  of  the 


86  THE  LYMPHATIC  SYSTEM. 

follicles  is  often  less  dense  than  that  at  the  periphery. 
Lymphatic  glands  may  be  regarded  as  highly  specialized  or 
compound  lymph-follicles. 


Fio.  38. 


• 


Lymph-follicle  (Flemming). 

Lymphoid  tissue  is  widely  distributed  through  the  body.  In 
a  diffuse  form  it  is  common  in  mucous  membranes  in  many 
situations,  especially  the  alimentary  canal.  Circumscribed 
lymph-follicles  are  most  typically  represented  by  the  solitary 
and  agminate  glands  of  the  intestines  ;  also  by  the  tonsils  and 
Malpighian  corpuscles  of  the  spleen.  The  lymphatic  glands 
and  t  hymns  are  also  composed  of  lymphoid  follicles. 

Lymphatic  glands  :  Interposed  in  the  course  of  the  lymph- 
atic vessels  in  many  situations,  notably  in  the  mesenteries, 
mediastina,  and  under  the  skin  in  certain  parts,  are  numerous 
lymphatic  glands.  These  are  oval  or  kidney-shaped  bodies, 
of  small  size,  with  a  depression  at  one  side,  the  hilum,  where 
the  bloodvessels  and  efferent  lymph-vessels  enter  and  leave 
the  gland. 

The  elements  of  lymphatic  glands  are  sustentacular  tissue, 


MEDULLARY  LYMPH-SINUSES.  87 

afferent  lymph-vessels,  lymph-sinuses,  dense  lymphoid  tissue, 
efferent  lymph-vessels,  and  bloodvessels.  Two  regions  can  be 
distinguished  in  them,  a  dense  peripheral  region,  the  cortex, 
and  an  opener  central  region,  the  medulla,  which  is  continuous 
with  the  hilum. 

The  sustentacular  tissue  forms  a  firm  fibrous  capsule  envel- 
oping the  gland,  which  sends  trabeccil&e  or  septa  inward 
toward  the  centre,  dividing  the  gland  into  a  number  of  radiat- 
ing rounded  lobules.  Delicate  retiform  tissue,  also  a  portion 
of  the  sustentacular  framework,  fills  the  entire  gland  and 
forms  the  basis  of  the  lymphoid  structures. 

The  afferent  lymph-vessels  are  a  number  of  vessels  or 
branches  which  enter  the  gland  at  scattered  points  over  the 
periphery,  emptying  into  the  peripheral  Ivmph-sinuses. 

The  cortical  portion  of  the  gland  is  mainly  made  up  of  typical 
lymphoid  tissue,  densely  packed  with  lymphoid  cells.  It  is 
divided  into  lobules  by  the  trabeculse,  and  each  lobular  mass 
of  lymphoid  tissue  is  surrounded  by  a  lymph-sinus.  The 
adenoid  tissue  in  the  outer  or  cortical  part  of  the  lobules 
forms  dense  continuous  masses ;  but  toward  the  centre  it 
breaks  up  into  branches  or  columns  of  lymphoid  tissue,  called 
lymph-cords,  which  project  into  the  medulla  and  are  sepa- 
rated by  the  medullary  lymph-sinuses  and  vessels. 

The  lymph-sinuses  are  open  channels  and  spaces  in  the 
retiform  tissue  where  the  lymph  is  more  free  to  flow  than  in 
the  dense  adenoid  tissue.  They  consist  of  the  same  open 
reticulum  which  forms  the  basis  of  the  lymphoid  tissue;  but 
very  few  lymphoid  cells  are  contained  in  the  meshes,  so  that 
the  lymph  is  afforded  free  passage  through  the  open  network. 
Into  these  sinuses  the  afferent  and  efferent  lymph-vessels 
freely  open. 

These  sinuses  may  be  divided  into  two  groups,  the  periph- 
eral sinuses  and  the  medullary  sinuses. 

The  peripheral  lymph-sinuses  surround  the  periphery  of  the 
lymphoid  tissue  which  makes  up  the  various  lobules,  and  the 
afferent  lymph  vessels  open  into  them.  They  consist  of  a 
narrow  space  intervening  between  the  capsule  and  trabeculse 
and  the  dense  lobular  adenoid  tissue. 

The  medullary  lymph-sinuses  are  located  in  the  central  por- 
tion of  the  gland,  and  consist  of  branching  open  sinuses  in- 


88  THE  LYMPHATIC  SYSTEM. 

tervening  between  the  columns  or  cords  of  dense  lymphoid 
tissue,  and  uniting  in  the  centre  to  empty  into  the  efferent 
lymph- vessels. 

The  cortex  of  lymphatic  glands  consists  of  the  lobules  of 
dense  lymphoid  tissue  surrounded  by  their  lymph-sinuses. 

The  medulla  is  a  smaller  region  in  the  centre,  continuous 
with  the  hilum,  in  which  the  tissue  is  opener.  It  is  composed 
of  the  medullary  lymph-sinuses,  the  columns  or  cords  of 
lymphoid  tissue,  the  branching  bloodvessels  and  efferent 
lymph-vessels,  and  some  connective  tissue. 

The  efferent  lymph-vessels  form  in  the  medulla  by  union  of 
the  smaller  channels  continuous  with  the  medullary  lymph- 
sinuses,  and  leave  the  gland  by  the  hilum. 

The  bloodvessels  enter  and  leave  mostly  by  the  hilum,  and 
in  the  medulla  break  up  into  networks ;  some  vessels  also  lie 
in  the  trabeculae. 

The  course  of  the  circulation  through  lymphatic  glands  is  as 
follows :  the  lymph  enters  by  the  afferent  vessels  at  various 
points  in  the  periphery,  passes  into  the  peripheral  lymph- 
sinuses,  then  percolates  through  the  lymphoid  tissue,  is  col- 
lected in  the  medullary  lymph-sinuses,  and  is  carried  away  by 
the  efferent  lymph-vessels.  At  the  same  time  the  blood  circu- 
lates through  the  gland,  and  the  serum  which  transudes  through 
the  capillary  walls  also  joins  the  efferent  stream  of  lymph. 

Thymus  gland  (Fig.  39) :  This  is  an  infantile  organ,  situ- 
ated at  the  base  of  the  neck  and  in  the  upper  mediastinum. 
In  the  embryo  it  first  appears  as  a  downgrowth  of  hypoblastic 
epithelium,  which,  dividing  and  subdividing,  takes  on  the 
character  of  a  compound  or  racemose  epithelial  gland.  Around 
this  epithelial  structure  soon  develops  from  the  mesoblast  a 
mass  of  lymphoid  tissue  in  such  abundance  as  to  encroach  on 
the  epithelial  growths,  causing  them  to  atrophy  and  cutting 
them  off  in  detached  masses,  which  in  the  mature  state  of  the 
gland  appear  as  scattered  rudimentary  epithelial  nodules,  the 
concentric  corpuscles.  The  organ  usually  reaches  it  maximum 
development  at  the  second  or  third  year  of  age,  and  then  in 
the  course  of  ten  or  fifteen  years  gradually  atrophies  and 
finally  disappears,  being  in  its  turn  replaced  by  fatty  and 
fibrous  tissue 

The  thymus  exhibits  a  medullary  and  a  cortical  region, 


THYMVS  GLAND. 


89 


and  consists  of  a  sustentacular  framework,  lymphoid  tissue, 
the  concentric  corpuscles  of  Hassall,  and  blood  and  lymphatic 
vessels. 

The  sustentacular  tissue  consists  of  a  fibrous  capsule  envel- 
oping the  gland,  trabeculae  extending  inward  dividing  the 
cortical  portion  into  lobes  and  lobules,  and  a  retiform  frame- 
work filling  the  entire  organ  as  a  basis  for  the  lymphoid 
tissue. 

The  body  of  the  gland  consists  throughout  of  lymphoid 

FIG.  39. 


Lobule  of  thym us  gland  (Schafer).    a,  cortex;  tr,  trabeculae;  6,  bloodvessels  in  the 
medulla  ;  c,  corpuscles  of  Hassall. 

tissue,  open  and  clearer  in  the  central  portion,  thus  constitut- 
ing the  medullary  region,  and  dense  in  the  outer  or  peripheral 
portion  forming  the  cortex. 

The  cortical  region  is  divided  into  lobes  and  lobules  by  the 
trabeculae  extending  inward  from  the  capsule. 

The  lobular  divisions  do  not  extend  into  the  medulla, 
which  thus  forms  a  common  core  from  which  all  the  lobules 
project. 

Scattered  about  in  the  medulla  are  the  concentric  corpuscles, 
or  corpuscles  of  Hassall,  small  spherical  bodies  having  a  gran- 
ular core  surrounded  concentrically  by  flat  squamous  epi- 


90  THE  LYMPHATIC  SYSTEM. 

thelioid  cells,  remains  of  the  original  epithelial  structure  of 
the  gland.  The  thyraus  is  abundantly  supplied  with  blood 
and  lymphatic  vessels. 

The  tonsils  and  solitary  and  agminate  glands  of  the  intes- 
tines are  lymphoid  glands,  and  are  described  in  connection 
with  the  alimentary  system. 

The  functions  of  lymphoid  tissue  and  glands  are  not  entirely 
understood,  but  some  important  purposes  which  they  serve 
are  known.  They  are  the  source  of  the  lymph-corpuscles 
and  leukocytes  of  the  blood.  The  lymphoid  cells  of  adenoid 
tissues,  after  undergoing  enlargement  and  certain  changes, 
enter  the  efferent  lymph-stream  as  lymph-corpuscles,  and 
after  passing  into  the  blood  they  form  leukocytes.  Lymphatic 
glands  also  serve  to  arrest  toxic  and  foreign  bodies  which 
enter  the  lymph-stream  ;  their  tissue  acts  as  a  sort  of  filter  in 
this  respect.  Thus,  in  cases  of  vaccination,  carcinoma, 
chancre,  and  many  similar  conditions,  the  virus  from  the 
affected  spot  is  taken  up  by  the  lymph-vessels,  but  is  arrested 
in  its  passage  at  the  next  group  of  lymphatic  glands,  which 
swell  up  and  become  inflamed,  thus  for  a  time  retarding  the 
progress  of  the  disease.  The  interchange  between  the  blood 
and  lymph  circulations  in  the  lymphatic  glands  may  also  be 
associated  with  some  sort  of  internal  secretory  process.  The 
special  purpose  of  the  thymus  is  obscure. 


CHAPTER  VIII. 
BLOOD   AND  LYMPH. 

The  blood  and  lymph  are  the  cellular  fluids  circulating 
about  the  body  in  the  circulatory  and  lymphatic  systems  and 
providing  for  body-nutrition.  They  convey  to  the  tissues 
the  gaseous,  fluid,  and  solid  pabulum  required  in  their  ana- 
bolism  or  upbuilding,  and  bear  away  from  them  the  waste- 
products  of  their  katabolism  or  downbreaking. 

Blood:  On  examining  fresh  blood  under  the  microscope 
we  observe  large  numbers  of  free  straw-colored  cells,  with 
here  and  there  a  colorless  cell,  suspended  in  a  clear  homo- 
geneous fluid.  The  blood,  then,  consists  of  two  portions — a 
fluid  .portion,  the  plasma,  and  free  blood-cells  or  corpuscles 
suspended  in  it. 

The  corpuscles,  again,  are  of  three  kinds — red  blood-corpus- 
cles, white  blood-corpuscles,  and  blood-plates. 

The  plasma  comprises  about  three-fifths  of  the  blood  ;  the 
corpuscles  about  two-fifths. 

The  blood  may  be  regarded  as  a  fluid  tissue,  the  corpuscles 
being  the  cellular  elements  and  the  plasma  the  intercellular 
substance.  It  differs  from  other  tissues,  however,  in  that  the 
intercellular  portion  is  not  produced  by  the  activity  of  the 
blood-cells  themselves,  but  is  derived  from  absorption.  The 
blood  belongs  to  a  class  of  tissues  that  is  sui  generis,  different 
from  and  coordinate  with  the  classes  of  epithelium,  connec- 
tive tissue,  etc.,  which  make  up  the  fixed  tissues.  Owing  to 
the  facility  with  which  it  can  be  examined  and  the  significant 
changes  which  it  exhibits  in  various  diseases,  the  histology  of 
the  blood  is  a  matter  of  great  importance  in  practical  medi- 
cine. 

Blood-plasma,  or  liquor  sftnguinis:  This  is  a  clear,  homogene- 
ous, colorless  fluid  comprising  about  three-fifths  of  the  volume 
of  the  entire  blood.  It  consists  of  water  holding  in  solution 

91 


92  BLOOD  AND  LYMPH. 

about  9  per  cent,  of  albuminous  substances,  mineral  salts, 
and  other  constituents.  These  substances  serve  as  pabulum 
for  the  nourishment  of  the  tissues.  It  readily  undergoes 
coagulation,  separating  into  clot  and  serum.  The  plasma 
originates  by  absorption  from  the  alimentary  tract.  Being 
homogeneous,  it  ordinarily  exhibits  no  structural  features  to 
the  microscope;  its  composition  is  a  matter  for  chemical 
study. 

Under  certain  circumstances,  however,  substances  or  par- 
ticles visible  to  the  microscope  appear  in  the  plasma.  After 
standing  for  some  time  specimens  of  fresh  blood  exhibit  in 
the  plasma  numerous  delicate  colorless  straight  filaments  of 
fibrin  interlacing  and  running  in  different  directions;  they 
often  radiate  from  points  or  centres,  and  at  these  centres 
blood-plates  are  often  situated.  These  filaments  consist  of 
fibrin  which  has  undergone  coagulation.  The  plasma  under 
the  microscope  often  has  a  yellow  tinge,  due  to  haemoglobin 
dissolved  out  of  the  red  corpuscles. 

Rhombic  crystals  of  haemoglobin  appear  in  blood  under 
proper  conditions  or  treatment.  Small  particles  of  fat  are 
sometimes  present  in  the  plasma,  especially  after  a  fatty 
diet. 

In  the  blood-plasma  are  frequently  to  be  seen  minute 
granules,  or  "blood-dust,"  both  in  normal  and  abnormal 
conditions.  Ordinarily  they  are  not  numerous,  but  occur 
singly  here  and  there.  Some  of  these  may  be  particles  of 
fat,  or  foreign  particles  accidentally  introduced.  In  most 
cases,  however,  they  seem  to  be  minute  bits  of  protoplasm, 
or  neutrophile  or  oxyphile  granules  extruded  from  leuko- 
cytes ;  their  nature  is  not  yet  fully  determined.  These  are 
very  minute  in  size,  variable  in  shape,  colorless  and  refractile, 
and  are  in  constant  very  active  oscillating  or  Brownian  move- 
ment. 

Red  blood-corpuscles  (Fig.  40)  are  also  called  erythrocytes, 
and,  most  appropriately,  colored  blood-corpuscles. 

The  red  blood -corpuscles  of  man  are  circular  disc-shaped 
cells,  between  7  and  8  /j.  in  diameter  (averaging  7.5  /./),  and 
about  2  p.  thick.  They  are  biconcave,  and  thinner  in  'the  centre 
than  at  the  edges,  so  that  their  color  is  lighter  and  paler  in 
the  middle  and  deepens  toward  the  periphery.  In  appearance 


RED  BLOOD-CORPUSCLES.  93 

they  are  homogeneous  throughout,  and  they  possess  no  cell- 
envelope.  They  contain  no  nuclei,  except  in  early  embryonic 
life  and  in  abnormal  conditions.  Their  color,  when  seen 
singly  or  in  thin  layers,  is  not  red,  as  the  name  indicates,  but 
a  characteristic  pale  yellow  with  a  slight  greenish  tinge  ;  it  is 
only  in  mass  that  they  produce  the  effect  of  red  color.  They 
are  soft,  elastic,  pliable,  almost  gelatinous.  As  they  flow 
through  the  capillaries  or  move  in  currents  in  the  micro- 
scopical specimen  they  change  shape  with  the  least  pressure, 
and  may  become  greatly  distorted  ;  but  on  release  from  re- 
straint they  resume  their  normal  discoid  shape. 

The  number  of  red  corpuscles  in  given  volumes  of  blood 
under  similar  normal  conditions  is  practically  constant,  and 
near  the  sea-level  in  adult  males 
is  about  5,000,000  in  each  cubic  FIG.  40. 

millimetre  of  blood ;  in  females, 
about  4,500,000.  In  very  vigor- 
ous individuals  the  number  of 
red  corpuscles  may  be  increased, 
even  up  to  6,000,000;  while 
with  increase  of  altitude  above 
sea-level  there  is  a  very  marked 
increase  in  their  number. 

When  a  drop  of  blood  is 
placed  under  the  microscope  the 
red  corpuscles  are  observed  to 

i  .,  .,  l  (>  ,.  i  Red  blood-corpuscles  of  man.  a,  sur- 

exhlblt,    for   a    time,    a    tendency  face  view  of  normal  corpuscles; 

to  form  rouleaux-that  is,  they  kgg^&SSr&S?^ 
become  arranged  or  adherent  —;  &££»  ;<— ^g 

together     evenlv     Side     DV     Side,  of  broken  corpuscles ;  g,  bent  and 

Ti  «T         /»        .  distorted  corpuscles:    h.  swollen 

like   a   pile   OI   COins.  and  decolorized  corpuscle. 

Crenation :  The  red  corpuscles 

are  so  delicately  adjusted  to  the  blood-plasma  that  they  are 
very  easily  affected  as  to  shape  by  any  alteration  in  the 
density  and  composition  of  the  medium  in  which  they  occur. 
One  of  the  commonest  of  these  change's  is  crenation.  This 
consists  of  a  shrinkage  of  the  corpuscle,  which  loses  its  dis- 
coid shape  and  becomes  spheroidal  or  irregularly  distorted, 
while  at  the  same  time  minute  rounded  or  spiny  projections 
appear  on  the  surface ;  of  these  spines  there  may  be  only  one 


O-C  ;  • 


94  BLOOD  A.\D  LYMPH. 

on  the  entire  corpuscle,  or  only  a  few ;  or  a  large  number 
studding  the  surface  of  the  much-shrivelled  spherical  cell. 
The  more  the  cell  is  contracted  the  greater  is  the  number  of 

spines. 

Crenation  is  caused  by  contraction  of  the  corpuscle  from 
loss  of  part  of  its  fluid  contents  through  osmosis,  and  occurs 
when  the  density  of  the  plasma  is  increased  by  evaporation 
from  exposure  to  the  air  or  by  the  addition  of  saline  or  other 
substances. 

Other  changes  of  form :  When  the  density  of  the  plasma 
is  diminished,  as  by  the  addition  of  water,  the  red  corpuscles 
through  osmosis  absorb  fluid,  swell,  and  become  spherical,  and 
at  the  same  time  lose  their  color,  the  haemoglobin  in  the 
corpuscles  leaving  them  and  passing  into  solution  in  the 
plasma  outside. 

Sometimes  the  substance  of  the  corpuscles  shrinks,  leaving 
artificial  empty  spaces  or  vacuoles. 

In  squeezing  blood  from  a  puncture  in  the  skin,  portions  of 
the  corpuscles  are  often  broken  off,  and,  assuming  a  rounded 
form,  appear  like  diminutive  corpuscles. 

At  other  times  the  corpuscles  appearyferer?,  twisted,  or  doubled 
up  in  the  form  of  a  hemispherical  bowl. 

Familiarity  with  the  changes  of  form  which  red  corpuscles 
undergo  under  changed  conditions  is  necessary  to  avoid  mis- 
taking them  for  morphologic  or  pathologic  abnormalities. 

In  various  disease-conditions  interesting  variations  from  the 
normal  are  exhibited  by  red  corpuscles,  as  the  presence  of 
nuclei,  and  abnormalities  in  size,  coloration,  and  consistency. 

The  function  of  the  red  blood-corpuscles  is  to  convey  oxygen 
from  the  lungs,  whSre  it  is  taken  up  by  the  hemoglobin,  to 
the  tissues,  where  it  is  given  out  for  nutritive  purposes. 

In  structure  they  appear  to  consist  of  a  pliable  and  elastic 
colorless  proteid  stroma,  in  which  haemoglobin  is  suspended  in 
solution  ;  the  form  and  consistency  of  the  cells  are  due  to  the 
stroma,  the  color,  to  the  haemoglobin.  They  do  not  exhibit 
ameboid  movement  or  cell  division.  Considering  their  lack 
of  nuclei,  and  of  other  vital  properties,  the  red  blood-corpus- 
cles must  be  regarded  as  a  very  degenerate  form  of  cell, 
exhibiting  few  characteristics  of  vitality  and  serving  the 
purely  mechanical  purpose  of  carrying  oxygen. 


DEGA  Y  OF  RED  BLOOD-CORPUSCLES.  95 

The  origin  of  red  blood-corpuscles  is  not  fully  determined. 
The  earliest  red  corpuscles  of  embryonic  life  originate  along 
with  the  bloodvessels  from  mesoblastic  cells  ("  angioblasts  ") 
which  form  a  protoplasmic  network,  in  the  substance  of 
which,  and  especially  at  the  intersections,  nuclei  proliferate 
and  accumulate.  These  masses  of  multinucleated  protoplasm 
break  up,  becoming  converted  into  cavities  filled  with  sepa- 
rated cells;  the  peripheral  protoplasm  and  nuclei  form  an 
endothelial  lining  to  the  cavity,  which  is  now  an  incipient 
bloodvessel,  while  the  central  mass  of  nucleated  protoplasm 
separates  into  amoeboid  nucleated  cells,  which  then  acquire 
haemoglobin  and  become  nucleated  red  blood-corpuscles. 
From  these  fi  blood-islands "  the  process  of  vessel  and  cor- 
puscle formation  proceeds  along  the  protoplasmic  strands. 

Thus  the  earliest  embryonic  red  corpuscles  are  nucleated, 
and  capable  of  self-reproduction  by  indirect  division  ;  these, 
however,  soon  disappear,  and  are  replaced  during  the  remain- 
der of  life  by  non-nucleated  corpuscles. 

The  most  probable  source  of  red  corpuscles  in  the  adult 
seems  to  be  the  bone-marrow.  As  described  above,  bone- 
marrow  contains  an  ample  network  of  expanded  vascu- 
lar sinuses,  and  one  class  of  the  cells  of  the  marrow 
consists  of  the  erythroblasts,  small  nucleated  haBmoglobin- 
containing  cells  capable  of  amoeboid  movement.  The  red 
corpuscles  are  probably  produced  from  these  cells,  but  in 
what  manner  is  not  known  ;  the  erythroblasts  themselves  may 
perhaps  be  descendants  of  the  nucleated  red  corpuscles  of  the 
embryo,  continued  in  existence  by  repeated  division. 

Other  theories  of  the  origin  of  red  corpuscles  have  been 
presented,  as  that  they  are  produced  from  leukocytes,  or  blood- 
plates,  or  in  the  spleen,  lymphatic  glands,  or  thy m us,  but 
these  suppositions  have  not  been  well  substantiated.  There 
is  a  constant  destruction  of  erythrocytes,  and  a  means  some- 
where in  the  body  by  which  they  can  be  actively  renewed. 
They  cannot  reproduce  themselves  by  division  ;  and  the  only 
known  seat  for  their  formation  supported  by  any  great 
probability  is  the  bone-marrow. 

Decay  of  red  blood-corpuscles  :  Erythrocytes,  like  all  other 
living  cells,  pass  through  a  life-cycle  of  development,  matur- 
ity, decay,  and  death.  The  red  corpuscles  seen  in  normal 


96  BLOOD  AND   LYMPH. 

blood  are  all  perfect  and  show  no  visible  signs  of  degenera- 
tion. What  becomes  of  them  when  they  decay  and  how  they 
are  removed  from  the  circulating  blood  is  not  entirely  known, 
but  it  is  supposed  that  the  spleen  and  liver,  especially  the 
former,  are  important  agents  in  their  removal  and  destruc- 
tion. 

Differences  in  vertebrate  red  blood-corpuscles :  Red  corpus- 
cles occur  only  in  the  blood  of  vertebrates,  that  of  inverte- 
brates containing  only  colorless  corpuscles.  The  different 
classes  of  vertebrates  exhibit  differences  in  the  characters  of 
the  erythrocytes  with  regard  to  shape,  nucleation,  and  size. 
All  mammals,  like  man,  have  non- nucleated  biconcave  circu- 
lar red  corpuscles,  except  the  camel  family,  in  which  they  are 
elliptical  (and  non-nucleated).  In  the  birds,  reptiles,  am- 
phibians, and  fishes,  the  red  corpuscles  are  elliptical,  nu- 
cleated, and  biconvex  (the  nucleus  causing  an  expansion  of 
the  corpuscle),  except  in  the  cyclostomata  or  lampreys  among 
fishes,  whose  corpuscles  are  circular. 

As  to  size,  the  erythrocytes  of  mammals  are  the  smallest, 
those  of  amphibians  the  largest. 

Among  mammals  the  red  cell  of  the  elephant  is  the  largest 
(9.2  //  in  diameter),  that  of  the  musk-deer  the  smallest ;  and 
it  is  the  smallest  known  of  all  animals  (2.5  //).  Human 
erythrocytes  are  among  the  largest  of  those  of  mammalia. 
The  erythrocytes  of  birds  and  fishes  are  much  the  same  in 
size;  the  corpuscle  of  the  fowl  is  about  12  /j.  long,  of  the 
pigeon  15  //,  of  the  carp  13  p.  The  frog's  red  corpuscles  are 
about  16  by  22  /Jt;  those  of  the  amphibian  proteus  35  by  58 
//. ;  while  those  of  the  amphibian  amphiuma  are  about  46  fj. 
wide  by  77  //  long,  the  largest  known,  and  visible  to  the 
naked  eye. 

The  number  of  the  erythrocytes  is  in  general  in  an  inverse 
proportion  to  their  size,  the  smaller  cells  occurring  in  greater 
numbers ;  thus,  the  red  corpuscles  of  the  frog  number  only 
404,000,  those  of  the  proteus  36,000  to  the  cubic  millimetre. 
Owing  to  this  inverse  relation  of  number  and  size  the  total 
mass  of  corpuscles  in  equal  volumes  of  blood  is  somewhat 
equalized ;  but  the  greater  the  number  of  corpuscles  the 
greater  is  their  total  surface ;  and  the  greater  their  surface  (as 
in  birds)  the  more  active  is  the  metabolism. 


STRUCTURE  OF  LEUKOCYTES.  97 

White  blood-corpuscles  (Fig.  41)  or  leukocytes,  are  most 
appropriately,  perhaps,  called  colorless  blood-corpuscles.  The 
leukocytes  of  man  are  of  several  varieties,  differing  in  some 
particulars  but  similar  in  their  general  characteristics. 

In  shape  when  at  rest  they  are  spherical,  but  during  their 
amoeboid  movements  they  are  irregular  and  changing  in 
form. 

In  size  the  different  varieties  range  from  about  7  to  15  /u  in 
diameter,  averaging  about  10  fj. ;  they  are  thus  somewhat 
larger  than  the  erythrocytes.  They  are  colorless,  refractile, 
and  granular  in  appearance. 

Their  surface  is  somewhat  adhesive  (unlike  the  red  corpus- 
cles), so  that  they  adhere  to  the  glass  in  microscopical  prepa- 
rations, and  in  the  blood-current  they  roll  slowly  along  at 
the  edge  of  the  stream  on  the  wall  of  the  bloodvessel. 

Thev  are  of  firmer  consistency  than  the  red  corpuscles,  and 
their  form  is  not  so  easily  affected  by  mechanical  influences 
or  changes  in  their  environment.  If  the  density  of  the  fluid 
in  which  they  occur  be  much  increased,  as  by  the  addition  of 
salts,  they  shrivel  somewhat;  while  if  the  density  be  dimin- 
ished by  dilution  with  water,  they  assume  the  resting  spheri- 
cal form,  become  swollen,  and  within  them  appear  coarse 
protoplasmic  granules  which  often  exhibit  the  Brownian 
movement. 

The  number  of  leukocytes  under  normal  conditions  is  about 
7500  or  8000  in  each  cubic  millimetre  of  blood  ;  the  number  is 
greater  in  young  children  and  during  pregnancy ;  and  during 
digestion,  as  three  or  four  hours  after  a  proteid  meal,  their 
number  is  normally  increased  about  one-third  (the  "digestion 
leukocytosis  ").  The  leukocytes  are  therefore  far  less  numer- 
ous than  the  red  corpuscles,  the  ratio  being  normally  about  1 
white  to  600  red.  In  pathological  conditions  the  number  of 
leukocytes  may  vary  widely.  Leukocytes  do  not  occur  in 
circulating  blood  alone,  but  are  also  met  with  as  lymph-cor- 
puscles in  the  lymphatic  system  ;  as  wandering  cells  in  the 
connective  tissues ;  in  enormous  accumulations  in  pus  as  pus- 
corpuscles,  etc. 

The  structure  of  leukocytes  is  that  of  typical  actively  vital 
cells.  They  have  a  cell-body  of  active  protoplasm,  well- 
marked  nuclei,  and  are  said  to  be  provided  with  centrosomes, 

7— Hist, 


98  BLOOD  AND  LYMPH. 

They  have  no  observable  cell-wall,  other  than  some  condensa- 
tion of  the  peripheral  protoplasm. 

The  nuclei  vary  in  the  different  varieties  of  leukocytes  as 
to  number,  form,  size,  and  staining  properties.  The  "  mono- 
nuclear"  leukocytes  contain  a  single  nucleus  each.  Other 
varieties  when  stained  appear  to  contain  about  three  separate 
rounded  nuclei ;  but  some  authorities  at  present  consider  that 
in  the  living  state  these  nuclei  are  in  most  cases  connected  by 
strands  of  the  nuclear  substance,  thus  forming  a  single  very 
irregular  nucleus  rather  than  three  separate  nuclei.  The 
possession  by  a  leukocyte  of  several  distinct  (or  multiple) 
nuclei  is  indicated  by  the  term  "  polynuclear " ;  while  the 
possession  of  single  variable  and  irregular  (or  multiform) 
nuclei  is  designated  by  the  term  "  polymorphonuclear." 

Inform  the  nuclei  range  from  spherical,  through  horseshoe- 
shaped  forms,  to  exceedingly  irregular  and  variable  coiled  and 
twisted  shapes.  Their  size  varies  from  those  that  are  large 
and  occupy  the  largest  part  of  the  cell  to  those  that  are  rela- 
tively smaller. 

The  nuclei  take  nuclear  and  basic  stains  with  more  or  less 
avidity ;  the  smaller  nuclei,  in  which  the  chromatin  is  more 
concentrated,  usually  stain  intensely  ;  \vhile  the  larger  nuclei, 
whose  chromatin  is  more  diffused,  are  less  deeply  colored. 

The  cell-bodies  of  leukocytes  consist  of  actively  vital  pro- 
toplasm. Sometimes,  especially  during  amoeboid  movement, 
two  parts  can  be  distinguished  in  the  body-protoplasm,  a  clear 
homogeneous  hyaline  peripheral  portion,  the  hyaloplasm,  and 
a  less  clear  granular  portion  in  the  interior  of  the  cell,  the 
granuloplasm.  Well-marked  granules  are  present  in  the 
bodies  of  some  varieties  of  leukocytes,  absent  from  others. 
The  granules  mostly  found  are  fine  neutrophile  granules  and 
coarse  oxyphile  granules  (e  and  «  granules  of  Ehrlich's  classi- 
fication) ;  fine  basophile  (8)  granules  also  occur  but  are  incon- 
spicuous. In  the  living  state  the  granular  appearance  of  the 
leukocytes  often  obscures  the  nuclei ;  but  on  treatment  with 
acetic  acid  the  granules  disappear,  the  cell-body  becomes  clear, 
and  the  nuclei  stand  out  prominently  as  about  three  spherical 
bodies. 

Varieties  of  leukocytes :  According  to  variations  in  size, 
nuclei,  granules,  and  staining-properties,  the  leukocytes  of 


TRANSITIONAL   LEUKOCYTE. 


99 


normal  human  blood  are  divided  into  five  classes,  namely : 
small  mononuclear,  large  mononuclear,  transitional,  poly- 
nuclear  (or  polymorphonuclear),  and  eosinophile. 


FIG.  41. 


Leukocytes  of  human  blood,  a,  small  mononuclear  leukocyte,  stained;  6,  large 
mononuclear  leukocyte,  stained;  c,  transitional  leukocyte,  stained;  d,  e, ,  poly- 
morphonuclear or  ne'utrophile  leukocyte,  living  appearance,  showing  distinc- 
tion of  hyaloplasm  and  granuloplasm  and  amoeboid  movement ;  /,  polymorpho- 
nuclear leukocyte,  in  fresh  state,  treated  with  acetic  acid ;  g,  h,  i,  polymorpho- 
nuclear leukocyte,  stained;  k,  eosinophile  leukocyte,  living  appearance;  I, 
eosinophile  leukocyte,  stained. 

The  small  mononuclear  leukocyte,  or  small  lymphocyte,  is 
about  6  to  8  micromillimetres  in  diameter  (about  the  same  as 
red  corpuscles),  and  has  a  single  large  spherical,  deeply  stain- 
ing nucleus,  surrounded  by  a  small  amount  of  faintly-stain- 
ing non-granular  protoplasm,  which  forms  a  small  cell-body. 
Morphologically  and  genetically  it  is  similar  to  or  identical 
with  lymph-corpuscles. 

The  large  mononuclear  leukocyte,  or  large  lymphocyte,  the 
largest  corpuscle  of  normal  blood,  is  12  to  15  micromillimetres 
in  diameter,  contains  a  single,  very  large,  rounded  nucleus 
that  does  not  stain  very  deeply,  and  has  a  large  body  of  non- 
granular,  faintly  staining  protoplasm.  Sometimes  no  sharp 
line  can  be  drawn  between  this  and  the  preceding  class,  all 
intermediate  gradations  of  size  and  coloration  being  present. 

The  transitional  leukocyte  is  like  the  large  mononuclear 


100  BLOOD  AND  LYMPH. 

form,  except  that  its  single  large  nucleus,  instead  of  being 
spherical,  is  more  or  less  indented  at  one  side,  tending  toward 
a  horseshoe  shape ;  the  body-protoplasm  also  sometimes  con- 
tains a  few  fine  granules.  In  the  shape  of  its  nucleus  it  is  an 
intermediate  form  between  the  large  mononuclear  and  the 
polymorphonuclear  variety.  It  is,  however,  closely  related  to 
the  former,  all  gradations  being  present  so  that  a  sharp  line 
can  scarcely  be  drawn  between  the  large  mononuclear  and  the 
transitional ;  on  the  contrary  (especially  with  respect  to  the 
absence  of  granules),  there  is  a  sharp  gap  between  the  transi- 
tional and  polymorphonuclear  varieties  not  filled  by  inter- 
mediate gradations.  Transitional  leukocytes  are  often  to 
be  regarded  simply  as  a  variety  of  the  large  mononuclear 
group. 

The  polymorphonuclear,  polynuclear ,  or  neutrophile  leukocyte 
is  about  10  micromillimetres  in  diameter,  has  a  large  cell- 
body  of  active  protoplasm,  containing  large  numbers  of  fine 
neutrophile  (s)  granules,  and  a  very  variable,  irregularly 
shaped,  deeply  staining  nucleus.  Often,  especially  after  the 
action  of  reagents,  the  nucleus  appears  to  consist  of  about 
three  separate,  rounded  nuclei ;  whence  until  recently  the  term 
polynuclear  was  the  prevalent  designation  of  this  leukocyte. 
At  present  the  opinion  is  gaining  ground  that  in  most  cases, 
instead  of  three  separate  nuclei,  the  living  corpuscle  contains 
one  long  twisted  and  irregular  nucleus,  so  that  the  name  poly- 
morphonuclear is  now  considerably  used.  This  is  the  most 
active  and  much  the  most  abundant  variety  of  leukocyte  in 
the  blood,  and  is  also  the  form  found  in  pus.  It  exhibits 
active  amoeboid  movements,  and  the  distinction  of  hyaloplasm 
and  granuloplasm  in  its  body  can  often  be  made  out. 

The  eosinophile  (or  oxyphile)  leukocyte  is  about  10  /2  in 
diameter;  its  nucleus,  except  that  it  stains  less  deeply,  is 
similar  to  that  of  the  polymorphonuclear  variety,  being  poly- 
morphous and  irregular,  or  perhaps  multiple  ;  the  body-proto- 
plasm is  crowded  with  conspicuous  coarse  spherical  oxyphile 
or  eosinophile  (a)  granules.  In  microscopical  specimens  the 
granules  surround  but  do  not  overlie  the  nuclei,  leaving  the 
latter  as  clear  spaces.  This  leukocyte  has  a  striking  appear- 
easily  recognized,  both  in  the  living  and  stained 
fe^the  least  common  variety  in  the  blood.  Its 

i    :_. 
BRA 


PROPERTIES  AND  FUNCTIONS  OF  LEUKOCYTES.      101 

wall  is  weak  and  easily  ruptured,  as  the  granules  often  ap- 
pear spreading  out  into  the  surrounding  plasma  without  any 
definite  boundary.  Intermediate  forms  between  the  eosino- 
phile,  the  polymorphonuclear,  and  the  mononuclear  leukocytes 
are  conspicuously  absent  from  the  blood. 

These  different  varieties  of  leukocytes  occur  in  normal 
blood  in  tolerably  constant  proportions  to  one  another,  aver- 
aging about  as  follows : 

Small  mononuclear  leukocytes 22  per  cent. 

Large  mononuclear  and  transitional  leukocytes  6    "      " 

Polymorphonuclear  leukocytes 70   "      " 

Eosinophile  leukocytes 2   "      " 

100 

Occasionally  a  stray  mast-cell  finds  its  way  into  the  blood. 
Variations  from  the  normal  occur  in  morbid  conditions ;  the 
total  number  of  leukocytes  and  the  relative  number  of  the 
different  varieties  may  be  altered,  or  entirely  new  forms  of 
leukocytes  (myelocytes)  may  appear. 

Vital  properties  and  functions  of  leukocytes :  Leukocytes  are 
typical  cells,  undifferentiated  and  independent,  actively  en- 
dowed with  all  the  essential  attributes  of  vitality.  They  are 
capable  of  undergoing  division,  direct  and  indirect.  They 
(especially  the  polymorphonuclears)  exhibit  active  auioaboid 
movements,  which  enable  them  to  make  their  way  through 
the  walls  of  the  capillaries  and  wander  about  in  the  tissues. 
By  means  of  their  amoeboid  movements  they  also  have  the 
power  of  surrounding  and  engulfing  within  their  protoplasm 
foreign  particles  and  living  parasites,  bacteria  and  protozoa. 
This  process  is  called  phagocytosis,  and  cells  which  engage  in 
it  are  called  phagocytes. 

The  act  of  phagocytosis  can  sometimes  be  observed  under 
the  microscope,  as  in  connection  with  the  malarial  protozoon, 
and  is  a  remarkable  and  interesting  sight.  The  leukocyte 
seems  capable  of  recognizing  the  presence  and  whereabouts 
of  the  parasite  at  a  distance  of  many  times  its  own  diameter, 
and  moves  upon  it  directly  and  with  distinct  purpose,  pushing 
the  red  corpuscles  aside.  By  protruding  pseudopodia  toward 


102  BLOOD  AND  LYMPH. 

the  parasite  and  drawing  itself  up  behind,  it  advances  with  a 
mode  of  locomotion  resembling  that  of  a  snail.  Finally,  it 
sends  processes  around  the  parasite  and  engulfs  the  latter  in 
its  body,  where  it  is  disintegrated.  The  leukocyte  seems  en- 
dowed with  intelligence,  purpose,  and  a  separate  individuality 
of  its  own,  vividly  analogous  to  the  psychic  manifestations  of 
macroscopic  animals. 

Chemical  substances  are  supposed  to  have  an  influence  on 
leukocytes,  some  attracting  them,  others  repelling  them  ;  this 
is  called  chemotaxis.  Positive  chemotaxis  consists  in  the  attrac- 
tion of  leukocytes  toward  certain  substances,  negative  chemo- 
taxis in  their  repulsion  from  other  substances. 

The  functions  of  leukocytes  are  not  entirely  understood. 
One  important  purpose  which  they  are  believed  to  subserve 
is  the  removal  and  destruction  of  foreign  noxious  substances 
and  parasites,  by  phagocytosis;  they  also  play  an  active  part 
in  the  repair  of  injuries,  in  immunity,  and  the  resistance  and 
reaction  of  the  body  to  morbid  processes. 

Origin  and  development  of  leukocytes :  The  small  mononu- 
dear  leukocytes  are  doubtless  derived  from  the  free  lymphoid 
cells  which  crowd  adenoid  tissues  ;  these  undergo  development, 
enter  the  lymph-stream,  and  are  thence  carried  into  the  blood. 

The  large  mononuclear  and  transitional  leukocytes  appear  to 
develop  from  the  small  mononuclears,  as  intermediate  grada- 
tions between  them  are  to  be  found  in  the  blood. 

The  source  of  the  polymorphonuclear  and  eosinophile  leuko- 
cytes is  not  so  obvious.  They  may  develop  from  the  mononu- 
clear variety — or,  as  has  been  suggested,  the  eosinophiles 
("  old "  forms)  may  develop  from  the  polynuclears,  and  the 
latter  ("adult"  forms)  from  the  mononuclears  (" young " 
forms) ;  as,  however,  there  are  no  intermediate  forms  between 
these  varieties  in  the  circulating  blood,  their  development 
from  one  another  must  take  place,  if  at  all,  somewhere  in  the 
viscera.  Or  perhaps  the  polynuclear  and  eosinophile  leuko- 
cytes originate  independently  in  some  of  the  viscera,  as  the 
spleen  or  bone-marrow. 

The  eosinophiles,  especially,  may  not  improbably  develop 
in  the  marrow,  as  in  the  latter  are  found  similar  cells  contain- 
ing oxyphile  granules.  Division  of  the  developed  leukocytes 
themselves  may  be  a  partial  means  of  their  production. 


LYMPH.  103 

Blood-plates  are  also  called  blood-plaques  or  platelets,  cor- 
puscles of  Bizzozero,  and  haeruatoblasts  (Fig.  42).     These  are 
small,     colorless,    hyaline, 
homogeneous     bodies,     of 
spherical  or  discoid  shape,  -.%:: 

between  2  and  4  micromil- 
limetres  in  diameter,  num- 
bering 200,000  to  400,000 
in  each  cubic  millimetre  of 
normal  blood.  On  exposure 
to  the  air  they  quickly  dis- 
integrate and  disappear,  so 
that  special  precautions  are  Q 

necessary  in  taking  a  speci-  Blood-plates. 

men  of  blood   to  preserve 

them.  They  occur  singly,  or  often  grouped  together,  in  the 
vicinity  of  granular  matter,  probably  the  debris  of  disinte- 
grated ""plaques.  They  often  form  centres  from  which  fila- 
ments of  coagulating  fibrin  radiate,  and  they  may  have  some 
relation  to  the  coagulation  of  the  blood.  They  have  been 
called  hnematoblasts  under  the  idea  that  they  are  developing 
forms  of  red  blood-corpuscles,  a  supposition  that  has  not  been 
confirmed.  Their  origin,  purpose,  and  significance  are  not 
definitely  known. 

Lymph,  the  fluid  which  flows  in  the  lymphatic  system,  con- 
sists of  a  fluid,  the  serum  or  plasma,  suspended  in  which  are 
free  cells,  the  lymph-corpuscles,  and  particles  of  fat.  The 
plasma,  or  liquor  lymphae,  is  similar  to  that  of  the  blood. 
The  lymph-corpuscles  are  leukocytes,  like  those  of  the  blood. 
Some  of  them  are  white  corpuscles  that  have  migrated  from 
the  capillaries  and  been  taken  up  from  the  tissues  by  the 
lymph-stream  ;  large  numbers  of  them,  however,  are  of  the 
small  mononuclear  type,  and  are  lymphoid  cells  carried  out 
of  the  adenoid  tissues  through  which  the  lymph-currents  pass. 
The  chyle  is  that  portion  of  the  lymph  that  is  collected  in  the 
lacteals  and  intestinal  lymphatics ;  it  is  of  the  nature  of  an 
emulsion,  opaque  and  white,  from  the  presence  in  the  plasma 
of  large  numbers  of  minute  particles  of  fat  absorbed  from 
the  intestines. 


CHAPTER    IX. 
BLOOD-GLANDS  AND  DUCTLESS  GLANDS. 

THE  lymphoid  glands  pertaining  to  the  lymphatic  system 
(lymphatic  glands,  tonsils,  thymus,  solitary  and  agminate 
glands,  etc.),  are  described  elsewhere. 

Other  structures,  "blood-glands,"  bear  the  same  relation  to 
the  blood-stream  that  lymphatic  glands  do  to  the  lymph  stream. 

Of  these  the  chief  representative  is  the  spleen,  an  important 
gland  partaking  somewhat  of  the  lymphoid  type.  In  some 
mammals  other  blood-glands  occur,  the  "  haemal  glands." 
Bone-marrow,  in  structure  and  function,  forms  a  sort  of  u  blood- 
gland."  Of  similar  nature,  perhaps,  are  the  small  coccygeal 
and  carotid  glands. 

The  active  ductless  glands  of  the  secretory  or  epithelial 
type  are  the  thyroid,  parathyroid,  adrenal,  and  pituitary  bod- 
ies ;  besides  these  are  the  ovary  (which  is.  of  unique  type),  the 
rudimentary  pineal  body,  and  certain  atrophic  foatal  structures 
about  the  genital  organs,  as  the  paradidymis  and  parovarium. 

The  functions  of  all  these  structures  are  more  or  less  obscure, 
but  (especially  if  the  theory  of  internal  secretion  is  true)  they 
may  be  considered  as  probably  belonging,  in  common,  to  the 
haemapoietic  (blood-forming)  and  hsemolytic  (blood-destroying, 
blood -purifying)  system,  contributing  corpuscular  and  chemi- 
cal constituents  to  the  blood  or  removing  from  it  effete 
materials. 

The  Spleen. 

General  structure  :  The  spleen  (Fig.  43)  consists  of  a  pulpy 
parenchyma  supported  in  a  reticular  sustentacular  tissue ; 
contains  numerous  lymphoid  follicles  (Malpighian  corpuscles), 
and  is  freely  supplied  with  bloodvessels  opening  directly  into 
the  reticular  spaces.  The  outermost  covering  of  the  spleen 
is  formed  by  the  peritoneum. 

104 


THE  SPLEEN. 


105 


The  sustentacular  or  connective-tissue  framework  of  the 
spleen  consists  of  a  firm  fibrous  capsule  enveloping  the  organ  ; 
of  fibrous  trabeculse  or  septa,  continuous  with  the  capsule, 
traversing  the  organ  in  all  directions  and  dividing  it  into  small 
compartments  or  lobules ;  and  of  an  open  reticular  tissue 
filling  these  compartments.  This  reticular  tissue,  which  is 
of  similar  character  to  the  retiform  basis  of  lymphoid  tissue, 
consists  of  fibres  interlacing  to  form  open  communicating 
spaces  or  sinuses,  wrhich  are  incompletely  lined  with  stellate 
flat  endothelioid  connective-tissue  cells.  These  spaces  open 
directly  into  the  bloodvessels,  and,  filled  with  free  cells  of 
various  kinds,  form  the  splenic  pulp. 

Scattered  involuntary  muscle-cells  occur  in  the  capsule  and 
larger  trabeculae. 

The  ample  bloodvessels  of  the  spleen  enter  at  the  hilum, 


FIG.  43. 


Portion  of  spleen,    a,  capsule  ;  6,  trabecula  ;  c,  splenic  pulp;  </,  Malpighian 
corpuscle ;  e,  portion  of  artery. 

and  the  larger  branches  lie  in  the  trabecular  tissue  as  they 
ramify  through  the  organ.  The  terminal  arteries  and  veins, 
instead  of  being  connected  by  capillaries,  open  into  the  reti- 
form sinuses  making  up  the  splenic  parenchyma,  so  that  the 
blood-current  percolates  through  this  spongy  tissue  in  its  pas- 


106          BLOOD-GLANDS  AND  DUCTLESS  GLANDS. 

sage  from  artery  to  vein.  Toward  the  terminations  of  the 
bloodvessels,  openings  appear  in  their  walls,  and  the  vessels 
become  lost  in  the  sinuses,  the  endothelium  of  the  tunica 
intima  merging  into  the  flat  connective-tissue  cells  incom- 
pletely lining  the  reticulum. 

The  parenchyma  of  the  spleen  is  mostly  made  up  of  the 
splenic  pulp.  This  consists  of  the  open  network  of  sinuses 
filled  with  plasma  and  free  cells,  some  of  which  are  peculiar 
to  this  situation,  others  derived  from  the  blood-stream  passing 
through.  The  free  elements  of  the  pulp  are  :  red  blood-cor- 
puscles in  great  abundance ;  lymphoid  cells  and  leukocytes  of 
all  kinds ;  large  multi nucleated  amoeboid  granular  cells  ;  and 
pigment-granules,  free  or  within  the  leukocytes  and  amoeboid 
cells,  derived  from  the  disintegration  of  the  hemoglobin  of 
broken-down  red  blood-corpuscles. 

The  spleen  is  supplied  with  lymphatic  vessels,  which  are 
much  less  conspicuous  than  the  blood-supply. 

Scattered  about  through  the  substance  of  the  spleen  are 
numerous  spherical  or  oval  nodules  or  follicles  of  typical 
lymphoid  tissue,  the  Malpighian  corpuscles.  These  occur  sur- 
rounding small-sized  arteries,  which  pierce  them  at  or  near 
their  centres. 

The  function  of  the  spleen  is  not  thoroughly  understood ; 
it  is  concerned  with  the  formation  or  purification  of  the  blood. 
It  may  be  a  seat  for  the  removal  of  worn-out  red  blood-cor- 
puscles. Whether  it  contributes  any  corpuscular  elements  to 
the  blood  has  not  been  settled. 

The  coccygeal  gland  (Luschka's  gland)  is  a  small,  round 
pea-sized  body,  near  the  tip  of  the  coccyx,  in  which  the 
middle  sacral  artery  terminates.  It  consists  of  a  plexus  of 
dilated  capillaries,  or  even  cavernous  blood-sinuses,  which 
are  surrounded  by  masses  of  granular  polyhedral  connective- 
tissue  cells.  The  gland  is  enveloped  by  a  fibrous  capsule, 
from  which  trabeculaB  pass  into  the  interior.  It  is  plentifully 
supplied  with  nerves.  Its  function  is  unknown. 

The  carotid  glands  are  small  bodies  situated  in  the  bifurca- 
tion of  the  common  carotid  arteries,  one  on  each  side.  Their 
structure  is  similar  to  that  of  the  coccygeal  gland. 


THE  THYROID   GLAND. 


The  Thyroid  Gland. 


107 


At  an  early  embryonic  period  this  gland  opens  into  the 
pharynx  by  an  outlet-duct ;  but  this  soon  disappears,  leaving 
the  alveoli  isolated  and  ductless. 

The  sustentacular  connective  tissue  of  the  gland  consists  of 
a  firm  fibrous  capsule  enveloping  the  organ  ;  trabeculce  or  septa 
(interlobular),  of  similar  fibrous  tissue,  which  divide  the  gland 
into  lobes  and  lobules ;  and  a  delicate  inter  alveolar  or  intra- 
lobular  tissue  between  and  supporting  the  secretory  alveoli. 

The  glandular  alveoli  are  spherical  or  oval  saccules,  without 

FIG.  44. 


Alveoli  of  thyroid  gland  (Dunham). 


outlet-ducts  and  entirely  closed  and  isolated  from  one  another 
(Fig.  44).  They  are  lined  with  a  single  layer  of  cuboidal 
epithelium-cells  with  prominent  nuclei.  The  cavities  or 
lumina  within  the  alveoli  are  of  considerable  size,  are  filled 
with  secreted  colloid  substance,  and  their  margins  often  have  a 
scalloped  appearance. 

The  bloodvessels  of  the  thyroid  are  exceedingly  ample,  and 
distribute  a  rich  capillary  network  about  the  saccules. 


108          BLOOD-GLANDS  AND  DUCTLESS  GLANDS. 

The  lymphatics  are  also  abundant,  and  through  them  the 
secretion  of  the  gland  is  probably  removed. 

The  function  of  the  thyroid,  as  indicated  by  its  rich  blood- 
supply  and  by  the  serious  consequences  of  loss  of  the  organ, 
is  of  great  importance.  Its  secretion  is  entirely  "  internal/' 
and  by  its  action  metabolism  and  cell-life  are  stimulated  and 
hastened,  obesity  diminished,  circulation  is  affected,  and  the 
cerebrum  stimulated. 

The  parathyroids  are  small  oval  ductless  glands  about  6  to 
10  mm.  long,  situated  near  the  thyroid,  usually  two  on  each 
side.  They  are  enveloped  by  delicate  fibrous  tissue,  and  the 
epithelial  columns  and  alveoli  are  separated  by  delicate  tra- 
beculaB  of  similar  tissue.  The  connective  tissue  is  very  vascu- 
lar. The  parenchyma  of  the  parathyroid  bodies  consists  of 
polyhedral  glandular  epithelium-cells  arranged  in  branching 
solid  columns  or  hollow  tubes,  some  of  which  occasionally 
contain  secreted  colloid  material.  The  epithelium  consists 
mainly  of  clear  cells  with  large  nuclei,  not  dissimilar  to  the 
cells  of  the  thyroid  gland.  A  few  of  the  epithelial  alveoli, 
however,  consist  of  larger  cells  with  granular  oxyphile  bodies, 
which  look  much  like  liver-cells ;  these  cells  are  altogether 
different  from  those  in  the  thyroid,  and  would  seem  to  estab- 
lish the  individuality  of  the  parathyroids  as  structures  inde- 
pendent and  distinct  from  the  thyroid. 

Little  has  yet  been  definitely  ascertained  as  to  the  functions 
of  the  parathyroids,  nor  their  genetic  or  vicarious  relations  to 
the  thyroid. 

The  Adrenal  or  Suprarenal  Glands. 

General  structure :  These  are  ductless  bodies  made  up  of 
columns  and"  masses  of  epithelium  supported  in  sustentacular 
tissue,  and  abundantly  supplied  with  bloodvessels  and  nerves 
(Fig.  45).  The  substance  of  the  gland  exhibits  two  parts, 
the  cortex  or  peripheral  portion,  and  the  medulla  or  central 
portion. 

The  sustentacular  connective  tissue  consists  of  a  fibrous 
capsule  enveloping  the  gland,  and  more  delicate  connective 
tissue  permeating  the  interior  and  lying  between  the  epithelial 
masses  and  vessels. 


THE  ADRENAL   OR  SUPRARENAL   GLANDS. 


109 


FIG.  45. 


The  cortex  consists  of  columns  or  nodules  of  epithelium 
(mostly  without  lamina),  separated  by  delicate  vascular  con- 
nective tissue.     The  epithelium-cells  are  polyhedral,  granular, 
and    sometimes    contain    fat- 
particles.     According  to  the 
arrangement  of  the  epithelial 
masses,  the  cortex  is  divided 
into  three  zones :  the  zona  re- 
ticularis, zona  fasciculata,  and 
zona  glornerulosa,  from  with- 
in outward. 

The  zona  reticularis,  the 
innermost  zone,  consists  of  a 
network  of  epithelial  columns 
anastomosing  with  one  an- 
other. In  the  zona  fascicu- 
lata, which  comprises  the 
largest  part  of  the  cortex,  the 
epithelial  columns  are  straight, 
parallel,  radiating,  and  sepa- 
rate from  one  another.  In 
the  zona  glomerulosa,  w7hich  is 
next  to  the  capsule,  the  epi- 
thelial columns  are  apparently 
coiled  and  convoluted,  ap- 
pearing on  section  as  separate 
rounded  nodules. 

Capillaries  and  lymph-pas- 
sages are  abundant  in  the  inter- 
columnar  cortical  tissue,  in 
close  relation  with  the  epi- 
thelium-columns, which  pos- 

,  Section    of 

sess  no  basement-membranes.      (Eberthi. 

The  medulla  of  the  adrenals 

is  quite  distinct  from  the  cortex  and  consists  of  epithelial 
masses  and  abundant  bloodvessels,  lymphatics,  and  nerves, 
supported  in  delicate  connective  tissue.  The  epithelium  is 
arranged  in  branching  and  anastomosing  nodules  and  columns 
or  closed  tubes  ;  the  cells  are  polyhedral  or  columnar.  Capil- 
laries are  numerous  and  large  venous  sinuses  are  present. 


human     adrenal    gland 
(Eberth).     1,  cortex;   2,  medulla. 


110          BLOOD-GLANDS  AND  DUCTLESS  GLANDS. 

Nerve-fibres  and  small  nerve-cells  are  abundant  in  the 
medulla. 

The  medullary  portion  of  the  adrenals  is  said  to  be  of  epi- 
blastic  origin,  an  outgrowth  from  the  primitive  spinal  cord, 
while  the  cortex  is  derived  from  the  mesoblast. 

The  internal  secretion  of  the  adrenals  seems  to  be  a  power- 
ful constrictor  of  the  bloodvessels  and  is  also  probably  a 
nervous  stimulant.  The  organ  is  by  some  regarded  as  a  part 
of  the  nervous  system. 

The  pituitary  body  (hypophysis  cerebri) :  The  posterior  lobe 
of  this  body  is  a  nervous  and  fibrous  structure,  derived  from 
and  a  part  of  the  brain.  The  anterior  lobe  of  the  pituitary  is 
of  the  nature  of  an  epithelial  ductless  gland,  being  embry- 
onically  an  epithelial  outgrowth  from  the  primitive  pharynx, 
which  is  afterward  cut  off.  It  consists  of  columnar,  closed 
tubular,  or  rounded  acini  of  polyhedral  epithelial  cells,  sepa- 
rated by  fibrous  septa.  The  acini  are  solid  or  a  few  may 
possess  lumina  containing  colloid  material.  Most  of  the  cells 
have  clear  bodies,  but  some  are  granular  and  oxyphile. 

The  pituitary  is  supposed  to  produce  an  internal  secretion 
which  has  some  influence  on  metabolism,  as  disease  of  it 
seems  to  be  associated  with  peculiar  anomalies  of  growth 
(acromegaly). 

The  pineal  body  (epiphysis  cerebri),  a  small  body  near  the 
corpora  quadrigemina,  has  the  structure  of  a  ductless  gland, 
but  is  probably  a  rudimentary  sense-organ.  It  consists  of  a 
number  of  rounded  acini  lined  by  epithelium  cells,  separated 
by  and  embedded  in  fibrous  tissue.  The  acini  contain  gritty 
particles  of  earthy  phosphates,  the  "  brain-sand,"  or  "  acer- 
vulus  cerebri.7' 


CHAPTER    X. 
THE    ALIMENTARY    SYSTEM. 

THE  alimentary  tract  is  an  apparatus  in  which  food,  the 
crude  material  of  which  the  organism  is  built  up,  is  received 
and  digested  by  the  action  of  various  secretions,  the  elab- 
orated products  absorbed  into  the  circulation,  and  the 
detritus  discharged.  It  is  a  complex  mechanism  with  many 
varied  parts  and  functions,  all  working  harmoniously  to- 
gether. It  consists  essentially  of  a  long  coiled  muscular 
tube,  the  alimentary  canal,  opening  at  each  end  on  the  surface 
of  the  body,  the  walls  of  which  contain  glandular  structures 
which  secrete  fluids  and  pour  them  into  the  canal  to  act  on  the 
raw  food-materials,  so  as  to  fit  them  for  absorption  and  nutri- 
tion. They  also  contain  absorbent  vessels  by  which  the 
digested  and  elaborated  food  is  introduced  into  the  circulation. 

The  different  parts  and  organs  of  this  system  are  the  mouth  ; 
teeth ;  tongue ;  salivary  glands  ;  tonsils  ;  pharynx  ;  oesophagus  ; 
stomach  ;  small  intestine ;  large  intestine ;  rectum  and  anus  ; 
peritoneum ;  liver  and  gall-bladder,  and  pancreas. 

The  Mouth. 

The  lining  of  the  mouth  consists  of  mucous  membrane, 
which  over  the  lips,  floor  of  the  mouth,  cheeks,  and  soft 
palate  rests  upon  the  voluntary  muscles  in  those  situations  ; 
and  over  the  bony  parts,  the  maxillary  and  palate  bones,  rests 
upon  the  periosteum. 

The  mucous  membrane  of  the  mouth  is  continuous  with  that 
of  the  pharynx  and  tongue  and  with  the  skin,  and  in  structure 
is  similar  to  the  latter.  It  consists  of  an  epithelial  lining,  a 
tunica  propria,  and  submucosa. 

The  epithelial  layer  is  the  representative  of  the  epidermis 
of  the  skin,  and  consists  of  stratified  squamous  epithelium. 

ill 


112  THE  ALIMENTARY  SYSTEM. 

The  lower  or  germinal  cells  are  rounded  and  spheroidal,  but 
as  the  layers  approach  the  surface  the  cells  become  gradually 
flatter  and  more  squamous  in  character.  This  layer  is  very 
similar  to  the  Malpighian  layer  of  the  skin.  On  its  free 
surface  the  squamous  cells  approach  a  hard  and  horny  condi- 
tion and  form  an  imperfect  representative  of  the  stratum 
corneum  of  the  epidermis. 

The  epithelial  layer  rests  on  the  tunica  propria,  a  firm 
fibrous  connective-tissue  structure  entirely  analogous  to  the 
corresponding  layer  of  the  cutis  vera.  The  outer  surface  of 
the  tunica  propria,  as  in  the  skin,  is  thrown  up  into  numerous 
small  rounded  elevations,  or  papUlce,  projecting  upward  into 
the  epithelium  ;  the  intervals  between  the  papillae  are  filled 
with  epithelium-cells. 

The  submucosa  consists  of  a  variable  amount  of  areolar  and 
connective  tissue  extending  from  the  tunica  propria  to  the 
underlying  structures.  It  contains  numerous  small  racemose 
mucous  glands,  whose  ducts  open  on  the  surface  of  the 
mucous  membrane.  Diffuse  h/mphoid  tissue  is  present  in  the 
submucosa  in  places,  especially  in  the  vicinity  of  the  fauces. 

The  Teeth. 

General  structure :  The  teeth  present  three  divisions  :  the 
crown,  projecting  above  the  gum;-  the  fane/,  buried  in 
the  gum;  and  the  neck,  at  the  junction  of  the  two  (Figs.  46 
and  47). 

Each  tooth  is  made  up  chiefly  of  dentine,  which  is  covered 
on  the  crown  by  enamel  and  on  the  fang  by  crusta  petrosa  or 
cement.  The  interior  of  the  tooth  is  a  cavity  inclosed  by  the 
dentine,  called  the  pulp-cavity,  filled  with  a  soft  tissue 
or  pulp. 

The  enamel  is  of  epiblastic  and  epithelial  origin  ;  the  den- 
tine and  crusta  petrosa  are  forms  of  connective  tissue  and  are 
of  mesoblastic  derivation. 

The  fangs  of  the  teeth  rest  in  sockets  of  the  jaw-bones 
lined  by  the  periodontal  membrane,  which  thus  separates 
the  tooth  from  the  bone.  This  membrane  is  a  vascular 
fibrous  structure  continuous  with  and  similar  in  structure  to 
the  periosteum  of  the  maxillary  bones ;  it  possesses  transverse 


THE  TEETH. 


113 


fibres,  like  the  fibres  of  Sharpey,  which  penetrate  both  the 
boiK.-  and  the  crusta  ]-  i   short  distance   and   hold    the 

teeth  firmly  in  place. 

The  enamel  of  the  teeth  is  a  very  hard  mineral  (calcareous) 


.  46. 


tiou  of  tooth  in  situ  (Waldo.  wl ;  2,  dcntint ; ;  ^fta  petrosa ; 

xillarybone;  c,  pulp-ca\it>. 


8— Hi?t. 


114 


THE  ALIMENTARY  SYSTEM. 


which 


substance,  almost  entirely  free  from  organic  matter,  win 
invests   the   crown.     It  is  disposed    in    slender   stra.ght   or 
slightly  wavy  rods  or  prisms,  of  about  six  sides  each,  which 
are  in  general  perpendicular  to  the  surface  of  the  dentine,  and 

.      Jo,  rr<i    _     ._J,     ,«l,:UU   £nn  ^T-ancvprsP 


are  held  together  by  cement. 


FIG.  47. 


The  rods  exhibit  fine  transverse 
markings.  At  eruption  and 
until  worn  off  by  attrition  the 
enamel  is  covered  with  a  thin 
epithelial  cuticle,  the  mem- 
brane of  Nasmyth,  the  remains 
of  the  enamel-organ. 

The  crusta  petrosa  is  a  thin 
layer  of  bone  formed  over  the 
surface  of  the  fang  of  the 
tooth  by  the  osteogenetic  action 
of  the  periodontal  membrane 
which  invests  it.  It  is  made 
up  of  bony  lamellae  of  the 
peripheric  type,  with  the  char- 
acteristic lacunae  and  canal i- 
culi. 

The  dentine,  or  ivory,  which 
forms  the  bulk  of  the  tooth,  is 
a  connective-tissue  structure, 
impregnated  and  hardened  by 
calcareous  salts.  It  contains 
large  numbers  of  minute  chan- 
nels or  passages,  the  dentinal 
tubules,  straight  or  slightly 
wavy,  with  short  lateral 
branches  ;  they  are  parallel  to 
one  another,  run  perpendicular 
to  the  surface  of  the  dentine, 
and  open  into  the  pulp-cavity. 
Each  tubule  contains  a  dentinal 
fibre,  a  process  from  one  of  the 
odontoblasts  or  connective- 
tissue  cells  in  the  pulp- cavity. 

Surrounding  each  tubule  is  a  dentinal  sheath,  a  membranous 
portion  of  the  calcified  matrix  especially  resistant  to  the  action 


Section  of  portion  of  tooth  ^Valdeyer). 
1,  crusta  petrosa,  showing  bony 
lacunae  and  lamellae  ;  2,  interglobu- 
lar  spaces— granular  layer  of  Pur- 
kinje;  3,  dentinal  tubules. 


DEVELOPMENT  OF  THE  TEETH.        115 

of  acid.  The  curves  or  undulations  of  the  various  tubules 
correspond  to  one  another,  and  appear  macroscopically  as  con- 
centric lines,  the  lines  of  Schreger. 

The  peripheral  portion  of  the  dentine  contains  numerous 
stellate  spaces  communicating  with  the  tubules,  and  in  the 
fang  with  the  canaliculi  of  the  crusta  petrosa;  these  are 
called  interglobular  spaces  or  dent'mal  lacunce,  and  from  its 
granular  appearance  the  zone  where  they  occur  is  called  the 
granular  layer  of  Purkinje.  These  lacunae  are  spaces  left  by 
incomplete  calcification,  and  contain  (at  least  at  an  early 
period)  stellate  connective-tissue  cells. 

The  incremental  lines  of  Salter  are,  roughly,  concentric  lines 
formed  by  interglobular  spaces  filled  with  an  imperfectly 
calcified  material ;  they  indicate  successive  zones  of  calcifica- 
tion of  the  dentine. 

The  pulp-cavity  is  a  space  in  the  interior  of  the  tooth  en- 
tirely enclosed  by  the  dentine,  except  at  the  apices  of  the 
fangs,  where  the  vessels  and  nerves  enter  from  the  dental 
canals  in  the  maxillary  bones.  The  pulp  consists  of  delicate 
connective  tissue  intermingled  with  bloodvessels  and  nerves. 
About  the  periphery  of  the  pulp-cavity,  lining  the  dentine 
which  forms  its  wall,  is  a  layer  of  modified  connective-tissue 
cells,  called  odontoblasts,  long  columnar  or  pyramidal  cells 
lying  perpendicular  to  the  dentine  and  sending  processes,  the 
dentinal  fibres,  into  the  dentinal  tubules. 

Development  of  the  teeth:  The  enamel  is  developed  from 
epithelium,  the  remainder  of  the  tooth  from  the  subepithelial 
connective  tissue.  Morphologically  teeth  are  usually  regarded 
as  modifications  of  the  papillae  of  the  mucous  membrane.  At 
the  beginning  of  the  development  of  the  teeth,  the  epithelium 
of  the  mucous  membrane  on  the  edge  of  the  jaw  grows  down- 
ward into  the  submucous  tissue,  dividing  into  a  process  for 
each  tooth.  These  processes  expand  below  and  narrow  above, 
forming  hemispherical  epithelial  masses,  called  enamel-organs, 
whose  connection  with  the  surface-epithelium  finally  becomes 
entirely  cut  off  or  reduced  to  a  mere  thread  of  epithelial  cells. 
Meantime  beneath  each  enamel-organ  the  connective  tissue 
becomes  vascular  and  rich  in  cells,  forming  a  papilla,  which 
grows  upward,  pushing  its  way  into  and  invaginating  the 
lower  surface  of  the  enamel-organ,  so  that  the  latter  forms  a 


116  THE  ALIMENTARY  SYSTEM. 

sort  of  hood  over  it.  The  connective-tissue  cells  at  the 
periphery  of  the  papilla  become  modified  and  arranged  in  a 
layer  of  odontoblaste,  which  then  produce  the  dentine. 

The  enamel-organ  consists  of  epithelium  cells  at  first  like 
those  of  the  lower  or  germinal  layers  of  the  mucous  mem- 
brane. The  outermost  layer  of  cells  of  the  enamel-organ 
become  of  a  columnar  or  cuboidal  type,  while  the  interior 
cells  degenerate  into  a  pulpy  mass  of  branched  cells  with 
anastomosing  processes;  the  cells  (a adamantoblasts ")  on  the 
lower  surface  of  the  enamel-organ  become  especially  long  and 
columnar,  and  these  cells  secrete,  or  become  transformed  into, 
columns  of  enamel  resting  on  the  surface  of  the  dentine. 

The  crusta  petrosa  is  bony  matter  subsequently  deposited 
on  the  fangs  by  the  osteogenetic  action  of  the  periodontal 
membrane. 

The  permanent  teeth  are  formed  in  a  similar  manner  to  the 
temporary  teeth,  their  enamel-organs  being  developed  from 
buds  given  off  from  the  epithelial  processes  which  form  the 
enamel-organs  of  the  temporary  teeth. 

The  Tongue. 

General  structure :  The  tongue  consists  of  a  mass  of  volun- 
tary muscle,  covered  with  mucous  membrane,  and  contains 
small  glands,  lymphoid  tissue,  blood  and  lymphatic  vessels, 
the  terminals  of  the  special  sense  of  taste,  and  other  nerves. 

The  muscular  substance  of  the  tongue  is  made  up  of  fas- 
ciculi of  voluntary  muscle-fibres  interlacing  and  running  in 
all  directions,  supported  and  bound  together  by  connective 
tissue.  A  vertical  fibrous  septum  divides  the  tongue  into  two 
lateral  halves. 

The  mucous  membrane,  which  is  continuous  with  that  of 
the  mouth  and  pharynx,  is  made  up  of  the  usual  three  layers, 
of  surface-epithelium,  tunica  propria,  and  submucous  tissue. 

The  epithelial  covering  consists  of  stratified  squamous  epithe- 
lium, the  surface-cells  becoming  rather  horny ;  it  is  very 
similar  to  that  lining  the  mouth  and  to  the  Malpighian  layer 
of  the  skin.  The  tunica  propria  is  a  firm  fibrous  membrane 
supporting  the  epithelium  and  giving  strength  to  the  mucous 
membrane.  The  submucosa  consists  of  areolar  tissue  con- 


PAPILLA  OF  THE  TONGUE. 


117 


tinuous  with  the  connective  tissue  investing  the  muscle-fas- 
ciculi in  the  interior.  The  glands  of  the  tongue  are  of  two 
kinds,  mucous  and  serous. 

The  mucous  glands  are  small  racemose  glands,  occurring  in 
considerable  numbers,  and  situated  in  the  submucosa  and 
between  the  muscular  fasciculi. 

The  serous  glands,  or  glands  of  Ebner,  are  small  racemose 
glands  occurring  in  the  vicinity  of  the  circumvallate  papillae 
and  discharging  their  watery  secretion  into  the  furrows  sur- 
rounding these  papillae. 

Nodules  and  masses  of  lymphoid  tissue  are  abundant,  under- 

FIG.  48. 


FIG.  49. 


Papilhe  uf  human  tongue  (Heitzmann). 

Fig.  48.— Filiform  papillae. 

Fig.  49.— Fungiform  papilla.   E,  epithelium ;  C,  tunica  propria,  showing  capillaries  ; 
L,  lymphoid  tissue  ;  .)f,  muscle. 

neath  the  epithelium,  at  the  base  of  the  tongue,  forming  the 
so-called  lingual  tonsil.  The  tongue  is  amply  supplied  with 
blood-  and  lymph  vessels  and  nerves  of  motion,  general  sensa- 
tion, and  special  taste-sense. 

Papillae  of  the  tongue  (Figs.  48,  49,  50) :  On  the  upper  sur- 


118 


THE  ALIMENTARY  SYSTEM. 


face  of  the  tongue  the  epithelium  and  tunica  propria  are  thrown 
up  into  papilla?,  which  are  of  three  or  four  kinds — filiform, 
fungiform,  circumvallate,  and  foliate. 

The  filiform  papilla  are  most  numerous  and  thickly  stud 
the  upper  surface  of  the  tongue.  They  consist  of  slender 
papillary  processes  of  the  tunica  propria,  surmounted  by 
slender  conical  projections  of  epithelium,  the  cells  of  which  at 
the  apex  are  horny  and  worn  by  attrition. 

The  fwngiform  papillce  are  larger  and  much  less  numerous 
than  the  filiform,  and  are  scattered  about  among  the  latter  as 
visible  red  points.  They  are  lower,  broader,  and  have  blunt 


FIG.  50. 


P 


Circumvallate  papillse,  of  rabbit  (Ranvier). 
p,  fibrous  core  of  papilla ;  g,  taste-buds  ;  n,  nerves ;  a,  gland  of  Ebner. 

rounded  tops.  They  consist  of  a  connective-tissue  core  pro- 
jecting from  the  tunica  propria,  with  minute  secondary  pro- 
jections from  its  surface,  all  covered  with  a  layer  of  epithelium. 
The  circumvallate  papillce  are  eight  to  twelve  large  broad 
papillse  arranged  in  a  V  shape  at  the  base  of  the  tongue.  The 
papilla?  are  similar  to  the  fungiform.  but  are  larger,  and  each 
is  surrounded  by  a  deep  furrow  or  ditch,,  so  that  the  papillse 


TASTE-BUDS  OF  THE  TONGUE.  119 

themselves  do  not  project  much  above  the  surrounding  sur- 
face, but  are  depressed. 

Scattered  about  in  the  epithelial  covering  of  the  sides  of  the 
furrow  are  numerous  taste-buds  or  taste-goblets,  oval  bodies 
made  up  of  modified  epithelium  and  containing  the  terminals 
of  the  nerves  for  the  special  sense  of  taste. 

The  serous  glands  of  Ebner  open  into  the  bottom  of  the 
furrows,  their  watery  secretions  apparently  aiding  the  solu- 
tion and  dissemination  of  substances  acting  on  the  taste-termi- 
nals. 

The  foliate  papillae  consist  of  a  few  parallel  folds  of  the 
mucous  membrane  on  each  side  of  the  base  of  the  tongue, 
forming  alternate  ridges  and  furrows  rather  than  papilla?. 
They  are  better  developed  in  some  of  the  other  mammals,  as 
the  rabbit,  than  in  man.  The  sides  of  their  furrows  contain 
taste-buds. 

The  taste-buds  are  terminals  for  the  special  sense  of  taste, 
and  occur  in  the  sides  of  the  furrows  of  the  circumvallate 
and  foliate  papillae,  with  a  few  scattered  about  in  the  epithe- 
lial layer  of  the  base  of  the  tongue,  the  lingual  surface  of  the 
epiglottis,  and  the  soft  palate.  They  are  oval  or  egg-shaped 
bodies,  with  the  long  axis  extending  through  the  entire  thick- 
ness of  the  epithelial  layer,  perpendicular  or  slightly  oblique 
to  the  surface.  They  are  made  up  of  two  kinds  of  modified 
epithelial  cells,  the  external  cortical  cells,  and  the  internal 
gustatory  cells.  The  outer  or  cortical  cells,  also  variously 
called  protective,  sustentacular,  supporting,  and  tegmental 
cells,  are  long,  slender,  flattened,  and  fusiform  cells,  each 
with  a  prominent  nucleus  near  its  middle. 

These  cells  are  arranged  longitudinally  so  as  to  form  an 
oval  body  or  covering  for  the  gustatory  celte,  which  lie  in  the 
axis  of  the  taste-bud.  The  latter  are  very  slender  linear 
neuro-epithelium  cells,  with  large  nuclei  near  their  middle 
causing  a  bulging  at  that  point.  They  extend  the  entire 
length  of  the  taste-bud,  surrounded  by  the  cortical  cells. 
Their  outer  ends  terminate  in  fine  hairs,  reaching  the  surface 
of  the  mucous  membrane  through  a  minute  opening  or  pore 
at  the  apex  of  the  taste-bud  ;  their  inner  ends  are  slender  or 
branched,  and  are  supposed  to  communicate  with  fibres  of  the 
special  nerves  of  taste. 


120  THE  ALIMENTARY  SYSTEM. 

The  Salivary  Glands. 

The  salivary  glands  are  the  parotid,  sublingual,  and  submax- 
illary,  besides  the  numerous  small  mucous  glands  (labial, 
buccal,  lingual,  and  palatal)  distributed  over  the  mucous  mem- 
brane of  the  mouth  and  tongue. 

General  structure  :  They  are  racemose  glands,  consisting  of 
saccules  and  ducts  supported  in  sustentacular  tissue,  divided 
into  lobes  and  lobules,  and  well  supplied  with  bloodvessels, 
lymphatics,  and  nerves. 

The  sustentacular  connective  tissue  consists  of  a  firm  fibrous 
capsule  enveloping  the  entire  gland,  sending  in  trabeculse 
(interlobular  septa)  which  separate  the  various  lobules  and 
bear  the  larger  vessels  and  nerves  and  the  interlobular  ducts, 
and  of  delicate  intralobular  tissue  penetrating  among  the  indi- 
vidual saccules,  and  forming  basement-membranes  for  their 
support. 

The  ultimate  saccules  or  alveoli,  the  secreting  portions  of 
the  glands,  are  lined  with  polyhedral  or  spheroidal  glandular 
epithelial  cells  of  the  serous  or  mucous  type. 

The  interlobular  ducts  are  lined  with  simple  columnar 
epithelium-cells,  which  toward  their  attached  bases  are  marked 
with  longitudinal  stria?  or  rods. 

In  the  intralobular  and  intermediate  ducts  the  epithelium- 
cells  forming  the  lining  become  lower  and  more  flattened. 

The  salivary  glands  are  amply  supplied  with  bloodvessels,  a 
capillary  plexus  surrounding  the  various  saccules.  The  lym- 
phatics consist  of  lymph-spaces  between  the  alveoli,  and  a 
system  of  vessels.  Fine  terminal  nerve-filaments  are  supplied 
to  the  secretory-epithelium  cells  in  great  abundance,  significant 
of  the  well-known  great  powrer  which  nervous  influences 
exert  on  the  secretary  action  of  these  glands. 

The  different  salivary  glands  vary  essentially  only  in  the 
character  of  their  secretory  elements.  The  parotid  is  a  serous 
gland,  the  sublingual  is  mucous,  the  submaxillary  mixed. 

In  the  parotid  gland  the  secreting  epithelium  and  alveoli 
are  of  the  serous  type.  The  saccules  are  lined  with  a  single 
layer  of  spheroidal,  granular,  deeply  staining,  opaque  cells, 
with  rounded,  central  nuclei.  In  the  resting  stage,  when 
charged  with  secretion,  the  cells  are  more  distended,  encroach 


SUBLINQUAL   GLAND.  121 

on  and  tend  to  fill  the  lumen,  contain  more  granules,  and  stain 
less  deeply.  In  the  exhausted  condition,  when  the  secretion  is 
discharged,  the  cells  are  somewhat  contracted  and  smaller, 
leaving  the  lumen  larger,  and  appear  darker,  more  opaque, 
and  more  deeply  stained  from  the  condensation  of  the  proto- 
plasm. 

In  the  sublingual  gland,  which  is  of  the  mucous  type,  the 
alveoli  are  rather  larger  than  in  the  serous  parotid,  and  have 
a  prominent  basement-membrane.  The  cells  lining  the  alveoli 
are  of  two  kinds,  the  ordinary  mucin-secreting  (central)  cells 
and  the  peripheral  or  demilune  cells. 


Mucous  alveoli  from  submaxillary  gland,  showing  mucinogenous  cells  and  demi- 
lunes of  Heidenhain  (Ranvier). 

The  former  make  up  much  the  larger  part  of  the  gland  and 
form  a  single  layer  of  spheroidal  epithelium-cells  lining  the 
lumen,  and  (except  where  the  demilunes  are  situated)  resting 
upon  the  basement-membrane.  These  cells  are  of  the  type 
characteristic  of  mucous  glands  ;  when  resting  and  distended 
with  secretion  they  are  swollen,  and  except  where  their  body- 
protoplasm  and  nuclei  are  pressed  toward  the  attached  bases 
the  cell-bodies  are  clear,  transparent,  and  do  not  stain  deeply. 
After  exhaustion  and  discharge  of  the  secretion  by  prolonged 
activity,  the  cells  become  smaller,  less  clear  and  transparent, 
and  the  more  concentrated  protoplasm  stains  more  deeply. 

In  places  between   the  mucinogenous  or  central  cells  are 


122  THE  ALIMENTARY  SYSTEM. 

situated  wedge-shaped,  pyramidal,  or  crescentic  bodies  called 
the  crescents  of  Gianuzzi  or  demilunes  of  Heidenhain,  each  of 
which  is  made  up  of  a  few  opaque  granular  deeply  staining 
dark  cells.  The  significance  of  these  demilune  cells  is  quite 
unknown,  though  several  views  as  to  their  nature  have  been 
propounded,  some  regarding  them  as  younger  germinal  cells 
destined  to  develop  into  mucinogenous  cells,  others  as  old  and 
exhausted  cells  which  have  not  taken  part  in  the  secretory 
process,  others  still  as  being  of  the  serous  type. 

The  submaxillary  gland  is  mixed,  some  of  its  alveoli  being 
serous,  like  the  parotid,  others  mucous  and  with  demilunes, 
like  the  subliugual. 

The  Tonsils. 

The  tonsils  (Fig.  52)  are  lymphoid  glands  located  between 
the  pillars  of  the  fauces  on  each  side.  They  consist  of  aggre- 
gations of  lymphoid  tissue  enveloped  by  a  fibrous  capsule 
formed  by  a  condensation  of  the  submucous  connective  tissue. 
They  are  covered  by  the  oral  mucous  membrane,  and  rest  on 
the  superior  constrictor  muscles  of  the  pharynx. 

The  mucous  membrane  forming  the  surface  of  the  tonsil 
dips  down  into  a  number  (ten  to  fifteen)  of  blind  depressions, 
or  crypts,  or  follicles,  each  of  which  is  lined  with  a  continua- 
tion of  the  stratified  squamous  epithelium  and  surrounded  by 
adenoid  tissue. 

Mucous  glands  are  present,  which  discharge  into  the  crypts. 
The  lymphoid  cells  infiltrate  the  tunica  propria  of  the  mucosa 
so  densely  as  to  obscure  it ;  they  even  penetrate  among  the 
epithelial  cells,  often  making  the  boundary  between  the  epithe- 
lial layer  and  the  subjacent  lymphoid  tissue  indistinct.  The 
lymphoid  cells  make  their  way  entirely  through  the  epithe- 
lium in  some  number,  and  appear  in  the  mouth  as  salivary 
corpuscles. 

The  lymphoid  tissues  in  the  tonsils,  base  of  the  tongue, 
palate,  and  pharynx  form  an  adenoid  ring  about  the  fauces  and 
pharynx.  These  structures  in  the  tongue  and  pharynx  are 
sometimes  called  the  lingual  and  pharyngeal  tonsils. 

The  saliva  as  secreted  by  the  salivary  glands,  is  a  homo- 


THE  SALIVA. 


123 


geneous  muco-serous  fluid  not  exhibiting  any  features  to  the 
microscope ;  but  as  it  occurs  in  the  mouth  it  contains  a  few 
adventitious  elements,  those  derived  from  the  local  tissues 
being  epithelium-cells,  leukocytes,  and  salivary  corpuscles; 
while  bacteria,  fungi,  food-particles,  and  other  foreign  objects 


FIG.  52. 


Section  through  crypt  of   tonsil  (Stohr).    e,  epithelium ;  /,  lymphoid  follicles ;  «, 
material  within  the  crypt,  composed  partly  of  escaped  lymphoid  cells. 

of  extraneous  origin  may  be  present.  The  epithelial  cells 
present  are  large  transparent  squamous  cells  with  prominent 
nuclei  and  coarse  granules  in  the  body  of  the  cell ;  their  edges 
are  often  curled.  The  leukocytes  that  may  be  present  are 
such  as  have  wandered  from  the  bloodvessels.  The  salivary 
corpuscles  are  lymphoid  cells  escaped  into  the  mouth  from  the 


124  THE  ALIMENTARY  SYSTEM, 

vicinity  of  the  tonsils ;  after  exposure  to  the  saliva  with  its 
low  specific  gravity  they  become  swollen  and  granular. 

The  Pharynx. 

The  walls  of  the  pharynx  consist  of  three  layers,  mucous 
membrane,  a  fibrous  coat,  and  a  muscular  layer.  The  upper 
part  of  the  pharynx,  above  the  palate,  belongs  to  the  respira- 
tory tract  and  is  lined  with  ciliated  epithelium  ;  the  lower 
part  belongs  to  the  alimentary  tract  and  is  lined  with  squamous 
epithelium. 

The  mucous  membrane  of  the  pharynx  is  continuous  with 
that  of  the  adjacent  cavities,  and  consists  of  three  layers, 
epithelium,  tunica  propria,  and  submucosa,  and  contains 
mucous  glands  and  lymphoid  tissue. 

The  epithelial  lining  in  the  upper  or  respiratory  portion  of 
the  pharynx  consists  of  stratified  ciliated  epithelium,  con- 
tinuous with  that  of  the  nasal  fossae  and  Eustachian  tubes ; 
in  the  lower  or  alimentary  portion  it  consists  of  stratified 
squamous  cells. 

The  tunica  propria  is  a  well-marked  fibrous  membrane, 
which  in  the  lower  part  of  the  pharynx  has  papillae  projecting 
among  the  squamous  epithelium. 

The  submueosa  is  a  layer  of  areolar  tissue  connecting  the 
mucosa  with  the  fibrous  and  muscular  tissues  beneath,  and 
containing  numerous  small  racemose  mucous  glands  and  nod- 
ules of  lymphoid  tissue. 

The  lymphoid  nodules  often  have  crypts,  like  those  of  the 
tonsils.  There  is  a  special  collection  of  lymphoid  tissue  on 
the  posterior  surface  of  the  pharynx  between  the  Eustachian 
tubes,  called  the  pharyngeal  tonsil. 

The  fibrous  coat,  or  pharyngeal  aponeurosis,  is  a  firm  fibrous 
membrane  lying  underneath  the  mucous  membrane,  thicker 
above,  and  becoming  thinner  below.  Posteriorly  it  is  thick- 
ened to  form  the  median  raphe. 

The  muscular  layer,  beneath  the  fibrous,  is  a  sheet  of  volun- 
tary muscle  made  up  by  the  three  constrictors  and  other 
muscles  of  the  pharynx. 

The  soft  palate  consists  of  a  thin  layer  of  the  voluntary 
palate  muscles  with  fibrous  aponeu roses,  lined  on  each  side  by 


THE  (ESOPHAGUS.  125 

mucous  membrane  like  that  of  the  mouth  and  pharynx,  of 
whose  walls  it  forms  a  portion.  The  epithelial  covering  con- 
sists of  squarnous  epithelium,  except  at  the  upper  part  of  the 
posterior  surface,  where  it  is  ciliated.  Mucous  glands  and 
lymphoid  tissue  are  abundant. 

The  (Esophagus. 

The  oesophagus  is  a  tube  whose  walls  consist  of  four  coats, 
mucous,  submucous,  muscular,  and  fibrous,  from  within  out- 
ward. 

The  mucous  membrane,  which  when  the  oesophagus  is  col- 
lapsed is  thrown  into  longitudinal  folds,  consists  of  the  epithe- 
lial covering,  the  tunica  propria,  and  the  muscularis  mucosse. 

The  epithelium  lining  the  lumen  of  the  tube  (Fig.  11)  is 
composed  of  stratified  squamous  cells,  flattened  on  the  surface 
and  gradually  becoming  thicker  and  more  spheroidal  in  the 
lower  layers;  it  is  similar  to  and  continuous  with  the  epithe- 
lium of  the  pharyngeal  mucous  membrane. 

It  is  underlaid  by  the  tunica  propria,  a  dense  fibrous  layer 
from  the  surface  of  which  papillae  project  upward  into  the 
epithelium. 

The  muscularis  mucosce  is  a  thin  layer  of  involuntary 
muscle-cells,  longitudinally  arranged,  separating  the  mucosa 
from  the  submucosa.  It  is  not  present  in  the  upper  part  of 
the  oesophagus,  but  appears  below  in  scattered  strands,  gradu- 
ally increases  downward,  and  in  the  lower  part  of  the  tube 
forms  a  well-marked  complete  ring. 

The  submucosa,  next  below,  is  a  layer  of  loose  areolar  tissue, 
which  permits  the  longitudinal  folding  of  the  mucous  mem- 
brane. It  contains  small  racemose  mucous  glands,  discharg- 
ing on  the  surface,  blood  and  lymphatic  vessels,  and  nerves. 

The  muscular  layer,  which  lies  beneath  or  outside  of  the 
submucous  coat,  is  composed  of  two  coats,  an  inner,  in  which 
the  muscle-cells  are  arranged  circularly  or  transversely ;  and 
an  outer,  in  which  they  are  longitudinal.  In  the  upper  portion 
of  the  oesophagus  the  muscle  is  striated  and  voluntary,  in  the 
lower  portion  non-striated  and  involuntary ;  in  the  middle  it 
is  mixed  and  exhibits  a  gradual  transition  from  one  kind  to 
the  other. 


126 


THE  ALIMENTARY  SYSTEM. 


The  outer  or  fibrous  investment  of  the  oesophagus  consists 
of  areolar  tissue  continuous  with  that  surrounding  the  adja- 
cent structures. 

FIG.  53.  The  Stomach. 

The  walls  of  the  stomach  (Fig. 
53)  may  be  divided  into  four 
coats,  which  are,  from  within 
outward,  the  mucosa  (containing 
two  kinds  of  glands,  peptic  and 
pyloric),  the  submucosa,  the 
muscular  layer,  and  the  serous 
or  peritoneal  covering. 

The   mucosa   consists  of   the 
epithelial  covering,  subepithelial 
connective     tissue,     muscularis 
miicosa?,    lymphoid    tissue,  and 
the  peptic  and  pyloric  glands. 
The    epithelial  lining   of  the 
stomach  consists  of  a  single  layer 
of   long   columnar    epithelium- 
cells,  with  their  nuclei  situated 
near  their  attached  bases ;  among 
the  columnar  cells   goblet-cells 
are  abundant.     The  surface  of 
the    stomach    dips    down    into 
closely  crowded  tubular  depres- 
*sions,  the  gastric  glands,  which 
arc  perpendicular  to  the  surface 
and  occupy  the  entire  thickness 
of  the  mucosa.    They  are  of  two 
kinds,  peptic  and  pyloric. 

The  peptic  or  cardiac  glands 
occupy  the  cardiac  portion  and 
fund  us  of  the  stomach,  yielding 
to  the  pyloric  glands' at  the 
pyloric  extremity.  The  peptic 
glands  are  simple  or  slightly 
divided  tubular  glands,  often 
with  the  lower  blind  ends  some- 


Diagrammatic  section  through  coats 
of  stomach  (Mall).  TO,  mucosa-  e 
epithelium;  d,  outlet  of  peptic 
gland;  mm,  muscularis  mucosse; 
am,  submucosa ;  cm,  inner  circular 
muscular  layer;  lm,  outer  longi- 
tudinal muscular  layer-  «  neri- 
toneum. 


THE  STOMACH. 


127 


FIG.  54. 


what  bent  and  coiled.  The  ducts  of  these  glands  are  short, 
and  lined  with  a  continuation  of  the  surface  columnar 
epithelium  ;  the  secreting  portions  of  the  tubules  join  the 
ducts  at  the  necks  of  the  glands.  Besides  occasional  goblet- 
cells,  the  fundus  or  secretory  part  of  the  peptic  glands 
is  lined  with  glandular  epithelium  of  two  kinds,  central  or 
chief  cells,  and  parietal  cells.  The 
central  or  chief  cells  are  rather  pale, 
faintly  granular,  columnar  cells, 
which  form  a  complete  lining  to 
the  lumen  of  the  glands ;  they  are 
supposed  to  secrete-  pepsin.  Be- 
tween them  and  the  basement- 
membrane,  and  often  causing  slight 
bulging  of  tire  latter,  are  scattered 
numerous  larger  oval  prominent 
cells,  the  parietal  cells,  supposed 
to  be  connected  with  the  secretion 
of  hydrochloric  acid ;  they  do  not 
form  a  complete  layer,  not  coming 
into  contact  with  one  another,  and 
do  not  usually  abut  on  the  lumen. 
Differences  in  the  appearance  of 
the  cells  when  charged  with  secre- 
tion and  when  exhausted  after  di- 
gestion occur,  analogous  to  the 
similar  changes  in  other  serous 
glands. 

The  pyloric  glands  (Fig.  54)  oc- 
cupy the  pyloric  end  of  the  stom- 
ach. They  are  compound  tubular 
glands,  and  are  similar  to  the  pep- 
tic glands,  but  have  longer  and 
wider  ducts  and  shorter  secreting 
portions,  their  lumen  is  opener 
and  greater  in  diameter,  they  are 
more  branched  (more  compound), 

and   they  contain  no  parietal  cells,  being  lined  with  central 
cells  only. 

The  subepithelial  connective  tissue  of  the  gastric  mucosa,  the 


Pyloric  glands  (Bohm  and  David- 
off). 


128  THE  A  LIMENTA  R  Y  S  YSTEM. 

representative  of  the  tunica  propria,  is  a  loose  and  delicate 
connective  tissue  extending  between  the  glands  and  providing 
basement-membranes  and  sustentacular  tissue  for  their  sup- 
port. It  contains  a  rich  capillary  plexus  enveloping  the 
glands.  Lymphoid  cells  are  scattered  about  and  diffuse 
lymphoid  tissue  occurs  in  places  in  the  subepithelial  tissue ; 
lymphpid  nodules  occur  especially  in  the  pyloric  region,  where 
they  are  called  lenticular  glands. 

The  mmcularis  mucosce  consists  of  two  thin  layers  of  in- 
voluntary muscle-cells,  the  outer  longitudinal,  the  inner  cir- 
cular ;  it  separates  the  mucosa  from  the  submucosa,  also  send- 
ing muscular  branches  up  among  the  gland-tubes.  When 
the  stomach  is  contracted  the  mucosa  is  thrown  into  folds 
or  rugaB,  permitted  by  the  loose  nature  of  the  submucosa. 

The  submucosa  is  a  loose  areolar  tissue  lying  beneath  the 
mucosa.  It  contains  the  larger  blood  and  lymphatic  vessels. 
The  muscular  coat  of  the  stomach,  lying  beneath  the  sub- 
mucosa, is  a  thick  layer  of  involuntary  muscle,  divided  in 
general  into  two  parts,  an  inner  arranged  circularly  and  an 
outer  longitudinal.  At  the  pyloric  orifices  the  circular  muscle 
is  thickened  to  form  a  sphincter. 

Outside  the  muscular  layer,  and  covering  the  outer  surface 
of  the  stomach,  is  the  serous  or  peritoneal  coat,  a  portion  of 
the  peritoneum  reflected  over  the  surface  of  the  organ.  It 
consists  of  a  thin  fibrous  membrane  covered  with  endo- 
thelium. 

The  stomach  is  richly  supplied  with  blood  and  lymphatic 
vessels,  the  larger  trunks  lying  in  the  submucous  tissue  and 
giving  off  capillaries  to  form  a  rich  network  in  the  mucosa. 

The  gastric  juice  consists  of  a  homogeneous  serous  secretion, 
containing  leukocytes  and  epithelium-cells  partly  digested, 
"  snail-shell-like  "  granules  probably  formed  by  the  action  of 
the  juice  on  mucin,  and  extraneous  food-particles  and 
bacteria. 

The  Small  Intestine. 

The  walls  of  the  small  intestine  are  composed  of  four  layers, 
mucous,  submucous,  muscular,  and  peritoneal,  from  within 
outward.  They  are  studded  with  papillary  structures  called 


/ 


THE  SMALL  INTESTINE.  129 

villi,  and  contain  two  kinds  of  secretory  glands,  intestinal  and 
duodenal,  lymphoid  structures,  bloodvessels,  lymphatics,  and 
nerves. 

The  mucous  membrane  is  thrown  into  transverse  and 
oblique  folds,  the  valvulce  conniventes.  Its  free  surface  is 
raised  in  papillary  projections,  called  vitti,  between  the  bases 
of  which  the  intestinal  glands  dip  down.  The  mucosa  con- 

FIG.  55. 


f -^--^ 


««*»          rt  in     •  i  B  ;  M 

. 


& 

-  - 

m         \   i.&o1 

Axial  section  of  villus  (Kultschitzky).  a,  epithelium  ;  b,  gob'.et-cell ;  d,  C9nnective- 
tissue  cell  of  basement-membrane ;  e,  smooth  muscle-cells ;  /,  reticulum  of 
tunica  propria ;  g,  central  lacteal. 

sists  of  a  lining  of  simple  columnar  epithelium,  which  differs 
somewhat  in  the  villi  and  the  glands ;  subepithelial  connec- 
tive tissue ;  adenoid  tissue ;  blood  and  lymph  vessels,  and 
the  muscularis  mucosse. 

The  villi  (Fig.  55)  are  minute  club-shaped  papillaB  about  a 

9— Hist. 


130  THE  ALIMENTARY  SYSTEM. 

(millimetre  long,  which  thickly  stud  the  inner  surface  of  the 
/entire  small  intestine.  In  places  they  exhibit  slight  constric- 
tions, called  Watney's  nodes.  They  are  covered  with  a  single 
flayer  of  long  columnar  epithelial  cells  (Fig.  13),  with  their 
f  nuclei  near  their  attached  bases.  The  protoplasm  of  the  free 
ends  of  these  cells  contains  fine  parallel  longitudinal  striae, 
giving  the  appearance  of  a  narrow  striated  border.  Goblet- 
cells  are  numerous  among  the  columnar  cells. 

The  epithelium-cells  rest  on  a  basement-membrane,  and  the 
framework  in  the  interior  of  the  villi  is  made  up  by  an  open 
connective-tissue  reticulum,  the  meshes  of  which  contain  free 
lymphoid  cells,  forming  a  diffuse  lymphoid  tissue.  The  core 
or  axis  of  the  villas  is  formed  by  a  small  lacteal,  a  lymphatic 
capillary  or  radicle ;  this  is  a  tube  or  sac  formed  by  a  single 
layer  of  endothelium-cells,  with  a  blunt  or  slightly  expanded 
blind  extremity  above  (toward  the  lumen  of  the  intestine),  and 
emptying  below  into  the  larger  lymphatic  vessels  of  the  sub- 
mucosa.  A  minute  artery  enters  each  villus  and  breaks  up 
into  a  rich  capillary  network  which  surrounds  the  lacteal. 
Muscular  projections  from  the  muscularis  mucosae  extend  up 
into  the  villi,  and  apparently  serve  by  periodical  contraction 
to  empty  them  of  their  contents.  The  Junction  of  the  villi  is 
to  absorb  the  digested  food-materials  from  the  intestinal  ogcnal 
into  the  blood  and  lymph  circulations.  They  especially 
absorb  the  insoluble  and  indiffusible  fatty  matters,  which  pass 
through  the  epithelium-cells  in  small  granules,  through  the 
reticulum  of  the  villus,  and  make  their  way  into  the  lacteal. 

The  intestinal  glands,  or  Jollities  of  Lieberkahn,  are  straight 
simple  tubular  glands  between  the  bases  of  thePvilli,  ard  dip 
down  to  the  muscularis  mucosse.  They,  and  the  surface  between 
their  orifices,  are  lined  with  a  single  layer  of  short  granular 
columnar  epithelial  cells,  with  nuclei  near  their  bases,  which 
rest  on  a  basement-membrane.  Goblet-cells  are  interspersed 
among  these  columnar  cells.  These  glands  occur  throughout 
the  small  and  large  intestines  ;  they  secrete  the  intestinal  juice 
and  also  perhaps  have  absorptive  functions. 

The  subepithelial  connective  tissue  of  the  mucosa,  the  ana- 
logue of  the  tunica  propria,  consists  of  a  delicate  reticular 
tissue,  embracing  the  glands  and  projecting  up  to  form  the 
framework  of  the  villi,  the  surface  condensed  into  a  basement- 


LYMPHOID   GLANDS.  131 

membrane.  It  contains  numerous  lymphoid  cells  and  diffuse 
lymphoid  tissue,  and  is  richly  supplied  with  lymphatics  and 
blood-capillaries.  The  muscularis  mucosce  consists  of  two  thin 
layers  of  involuntary  muscle,  the  inner  circular,  the  outer 
longitudinal.  It  lies  just  below  or  outside  of  the  extremities 
of  Lieberkiihn's  glands,  and  separates  the  mucosa  from  the 
submucosa.  It  sends  fibres  up  into  the  villi. 

The  submucosa  of  the  small  intestine  is  a  loose  areolar 
layer,  permitting  some  play  between  the  mucous  and  muscular 
coats.  It  contains  the  larger  blood  and  lymphatic  channels, 
which  send  capillaries  into  the  mucosa,  and  a  nerve-plexus,  the 
plexus  of  Meissner. 

The,  duodenal  glands,  or  glands  of  Brunner,  are  rounded 
compound  racemose  or  perhaps  tubular  glands,  of  the  s&&wT 
type,  located  in  the  submucosa  of  the  duodenum.  Each 
empties  by  a  long  outlet-duct  which  pierces  the  muscularis 
mucosa?  and  traverses  the  mucosa  to  the  surface,  parallel  to  the 
glands  of  Lieberkiihn.  Their  cells  are  similar  to  those  of  the 
intestinal  glands. 

The  lymphoid  glands  of  the  small  intestine  are  definite  and 
dense  masses  of  lymphoid  tissue,  which  occur  in  addition  to 
the  diffuse  adenoid  tissue  of  the  mucosa ;  they  are  of  two 
kinds,  solitary  and  agminate.  The  solitary  glands  are  spherical 
nodules  or  follicles  of  lymphoid  tissue,  occurring  singly,  and 
circumscribed  by  a  condensation  of  the  surrounding  connective 
tissue.  They  are  situated  in  the  submucosa,  or  may  extend 
into  the  mucosa  and  even  to  the  epithelial  covering.  They 
occur  throughout  the  small  and  large  intestines,  but  are  more 
numerous  toward  the  lower  part  of  the  ileum  and  the  begin- 
ning of  the  colon. 

The  agminate  glands,  or  Pgz^ris  patches,  are  aggregations 
of  a  number  of  solitary  lymph-follicles  placed  in  juxtaposi- 
tion, and  sometimes  surrounded  by  looser  adenoid  tissue. 
They  occupy  the  submucosa,  some  of  the  follicles  in  places 
also  piercing  the  muscularis  mucosaB  and  extending  into  the 
mucosa  and  to  the  surface-epithelium.  They  form  longitudi- 
nal patches  two  to  eight  centimetres  long  opposite  the 
mesenteric  attachment  of  the  intestine,  and  are  most  abundant 
in  the  lower  portion  of  the  ileum. 

The  muscular   coat  of  the  small   intestine   comprises  two 


132  THE  ALIMENTARY  SYSTEM. 

layers  of  involuntary  muscle,  a  thick  inner  circular  layer,  and 
a  thinner  outer  longitudinal  layer.  Between  these  two  is  the 
nerve-plexus  of  Auerbach. 

The  serous  or  peritoneal  coat  is  the  portion  of  the  peri- 
toneum reflected  over  the  intestine  to  form  its  outer  covering. 

The  intestine  is  wrell  supplied  with  blood  and  lymphatic 
vessels,  the  larger  channels  of  which  are  in  the  submucosa  and 
send  capillary  plexuses  into  the  mucosa.  The  lacteals  con- 
stitute an  important  origin  of  the  lymphatic  system. 

The  intestine  is  also  supplied  with  two  plexuses  of  nerves ; 
the  plexus  of  Auerbach  is  a  network  of  fibres  with  minute 
ganglia  at  their  intersections,  situated  between  the  two  layers 
of  the  muscular  coat ;  the  plexus  of  Meissner,  situated  in  the 
submucous  coat,  is  connected  with  and  similar  to  that  of 
Auerbach,  but  is  made  up  of  finer  fibres  and  finer  meshes. 

The  Large  Intestine. 

The  large  intestine  has  four  coats,  mucous,  submucous, 
muscular,  and  serous,  and  contains  glands  of  Lieberkiihn  and 
solitary  glands.  It  resembles  the  iletim  in  structure,  but  has 
no  villi  or  Peyer's  patches,  and  the  outer  muscular  coat  is  dif- 
ferently arranged. 

Its  mucosa,  lined  with  simple  columnar  epithelium,  is  every- 
where studded  with  Lieberkiihn's  follicles,  supported  in  a 
delicate  subepithelial  retiform  tissue,  which  is  well  supplied 
with  diffuse  lymphoid  tissue,  capillaries,  and  lymphatics. 

The  glands  of  Lieberkuhn  are  rather  larger  than  in  the 
small  intestine,  but  are  lined  with  similar  cells,  among  which, 
however,  goblet-cells  are  much  more  abundant. 

The  muscularis  mucosce,  vascular  and  nervous  plexuses,  sub- 
mucous  and  peritoneal  coats  are  much  the  same  as  in  the  small 
intestine,  and  solitary  glands  are  abundant. 

The  muscular  coat  has  the  usual  inner  circular  layer,  rather 
thin  in  most  places.  The  outer  layer  of  longitudinal,  non- 
striated  muscle,  however,  instead  of  forming  a  complete  sheet, 
is  limited  to  three  longitudinal  bands,  which  are  shorter  than 
the  other  structures,  and  thus  cause  the  colon  to  be  puckered 
or  sacculated. 


THE  LIVER.  133 

The  appendix  vermiformis  is  similar  in  structure  to  the 
colon.  The  raucosa  contains  well- formed  glands  of  Lieber- 
kiihn,  and  it  and  the  loose  submucosa  contain  numerous  lym- 
phoid  follicles  and  diifuse  lymphoid  tissue.  The  muscular 
coat  and  peritoneal  covering  form  the  outer  layers. 

The  rectum  has  a  mucous  and  submucous  layer  similar  to 
that  of  the  large  intestine.  The  covering  of  simple  columnar 
epithelium  changes  at  the  anus  into  the  stratified  squamous 
variety. 

The  internal  circular  muscular  layer  is  thickened  to  form 
the  internal  (involuntary)  sphincter,  over  which  the  longitudinal 
muscular  layer  spreads  out  to  form  a  complete  investment 
(instead  of  consisting  of  three  bands  only).  The  external 
sphincter  is  a  thin  voluntary  muscle  surrounding  the  anus. 
The  lower  portion  of  the  rectum  has  no  peritoneal  covering. 

The  peritoneum  is  a  large  serous  or  lymph  sac,  formed  by  a 
typical  serous  membrane  covering  the  walls  of  the  abdomen 
(parietal  layer)  and  the  abdominal  viscera  (visceral  layer).  It 
enables  the  latter  to  move  freely. 

It  is  mainly  made  up  of  &  fibrous  membrane  containing  lym- 
phatics and  bloodvessels,  lined  on  the  free  surface  with  poly- 
gonal endothelium-cells,  between  which  in  places  are  lymph- 
stomata. 

Beneath  it  is  a  variable  amount  of  areolar  subserous  or  sub- 
peritoneal  tissue,  in  which,  especially  in  the  parietal  layers, 
mesenteries,  and  omenta,  masses  of  fatty  tissue  often  accumu- 
late. 

The  blood,  lymphatic,  and  nerve  trunks  which  supply  the 
intestines  are  situated  in  the  mesenteries,  which  also  contain 
numerous  lymphatic  glands. 

The  Liver. 

The  liver  is  usually  classed  as  a  gland,  producing  the  bile 
as  a  secretion  (external).  It  is  much  more  than  this. 

All  the  venous  blood  from  the  stomach  and  intestines,  con- 
taining the  products  of  digestion  absorbed  from  the  alimentary 
canal,  is  collected  in  the  portal  vein,  redistributed  in  capillaries 
and  passed  through  the  liver  as  through  a  sieve,  and  is  acted 


134 


THE  ALIMENTARY  SYSTEM. 


on  by  intimate  contact  with  the  liver-cells  before  being  again 
collected  in  the  hepatic  vein  and  discharged  into  the  general 
circulation. 

In  its  passage  through  the  liver  the  constituents  of  the 
blood  are,  in  ways  not  well  understood,  altered  by  the  action 
of  the  liver-cells  for  purposes  useful  to  the  animal  econ- 
omy. This  action  on  the  blood,  of  which  the  glycogenic 
and  urea-forming  functions  are  known  instances,  partakes  of 
the  nature  of  "  internal  "  secretion.  The  liver  also  serves  as 
a  storehouse  for  certain  substances.  As  a  gland  the  liver  is  of 
the  compound  tubular  type  ;  but  in  mammalia  it  is  constructed 
more  with  reference  to  its  functions  bearing  on  the  blood,  and 
its  glandular  structure  is  masked  and  obscure. 

General  structure  :  The  liver  consists  of  masses  of  epithelial 
cells  divided  into  small  lobules  or  acini,  supported  in  susten- 
tacular  tissue,  and  contains  a  network  of  outlet  bile-ducts  and 

FIG.  56. 


Lobules  qf  liver  of  pig,  showing  interlobular  septa  and  a  portal  tract  (Klein). 

three  systems  of  bloodvessels  :  the  hepatic  artery,  portal  vein, 
and  hepatic  vein  ;  besides  scanty  lymphatics  and  nerves. 

The  sustentacular  or  connective  tissue  of  the  liver  consists 
of  the  capsule  (of  Glisson),  interlobular  septa,  and  the  "  portal 
tracts." 

The  capsule  of  Glisson  is  a  fibrous  envelope  investing  the 
liver,  beneath  the  peritoneum.  The  interlobular  septa 


are 


THE  LIVER.  135 

delicate  partitions,  poorly  marked  in  the  normal  human  liver, 
which  separate  the  hepatic  lobules.  The  portal  tracts  are  well- 
marked  processes  of  fibrous  tissue  passing  into  the  liver  with 
the  portal  vein,  hepatic  artery,  and  bile-ducts,  and  surround- 


FIG.  5' 


Diagram  of  portion  of  a  lobule  of  the  liver  (Dunham),  a,  intralobular  vein,  receiv- 
ing intralobular  capillaries  ;  b,  branches  of  portal  vein  ;  c,  branches  of  hepatic 
artery  ;  d,  bile-ducts ;  e,  lymph-vessel ;  /,  liver-cells  ;  g,  junction  of  two  lobules. 

ing,  accompanying,  and  supporting  these  vessels  in  all  their 
subdivisions  and  ramifications  throughout  the  organ.  These 
tracts  are  situated  at  the  junction  of  three  or  four  lobules,  and 
send  lamellae  between  the  adjacent  lobules  continuous  with 
their  interlobular  septa,  indeed  forming  the  only  portions  of 
these  septa  conspicuous  in  the  normal  liver. 

In  cross-section  the  portal  tracts  are  therefore  triangular  or 
stellate,  and  in  each  may  be  seen  three  or  more  vessels,  the 
largest  a  branch  of  the  portal  vein  ;  and  a  branch  of  the  hepatic 
artery  and  a  bile-duct,  which  are  much  smaller.  Within  the 
lobules  of  the  liver  connective-tissue  elements  are  very  scanty, 
being  represented  only  by  the  endothelium  of  the  capillaries. 


136  THE  ALIMENTARY  SYSTEM. 

The  hepatic  artery  is  a  small  vessel,  the  branches  of  which 
accompany  those  of  the  portal  vein  in  the  portal  tracts.  It 
supplies  blood  for  the  nourishment  of  the  connective  tissue 
and  vessels  of  the  liver. 

The  bile-ducts  collect  and  convey  the  bile  from  the  secreting 
lobules  to  the  hepatic  duct,  the  general  outlet-duct  of  the  liver. 
They  lie  in  the  portal  tracts.  The  smaller  ducts  are  lined 
with  simple  columnar  epithelium  (by  which  they  may  be  dis- 
tinguished from  the  accompanying  arteries  of  corresponding 
size),  resting  on  a  basement-membrane.  As  the  ducts  unite 
and  become  larger  the  connective  tissue  by  which  they  are 
surrounded  forms  a  thicker  layer,  in  which  elastic  elements 
and  involuntary  muscle-cells  appear. 

The  portal  vein  is  the  main  afferent  bloodvessel  of  the 
liver,  conveying  into  it  the  venous  blood  from  the  digestive 
organs.  Its  branches  follow  the  portal  tracts,  and  are  the 
largest  and  thinnest- walled  of  the  vessels  in  the  latter.  As  its 
branches  lie  always  in  the  septa  between  the  lobules,  they  are 
called  the  interlobular  veins.  They  divide  into  capillaries, 
which  penetrate  and  converge  to  the  interior  of  the  lobules, 
and  there  empty  into  the  radicles  of  the  hepatic  vein. 

The  hepatic  veins  are  the  efferent  bloodvessels  of  the  liver. 
They  begin  by  the  blind  hepatic  radicles  or  intralobular  veins, 
which  lie  in  the  centre  or  axis  of  the  lobules  and  receive  the 
intralobular  capillaries.  The  intralobular  veins  empty  into 
larger  branches,  the  sublobular  veins,  the  union  of  which  forms 
the  hepatic  veins. 

The  lobules  or  acini  of  the  liver  are  polyhedral  in  shape 
from  mutual  pressure,  and  about  a  millimetre  in  diameter. 
They  are  separated  from  one  another  by  the  interlobular  septa 
of  the  sustentacular  tissue,  though  in  man  these  septa  are 
incomplete  and  the  boundaries  of  individual  acini  often  diffi- 
cult to  determine.  In  cirrhosis  of  the  liver  and  in  some  mam- 
mals the  septa  are  complete  and  well  marked. 

Each  lobule  is  made  up  of  liver-cells,  intralobular  capilla- 
ries, bile-passages  between  the  cells,  and  an  intralobular 
vein  in  the  centre  or  axis  of  the  lobule.  The  acini  are  built 
around  the  intralobular  veins  as  axes,  and  their  bases  abut  on 
the  sublobular  veins  into  which  these  veins  empty. 

The  liver-cells  are  polyhedral,  nucleated,  glandular  epithe- 


INTRALOBULAR  CAPILLARIES. 


137 


Hum-cells,  which  often  contain  granules  and  fat-particles. 
Differences  as  to  granularity,  etc.,  occur  in  the  appearance  of 
these  cells  in  the  various  stages  of  digestion,  as  between  fast- 
ing periods  and  after  eating.  The  liver-cells  fill  the  acini  in 
a  mass  interrupted  only  by  the  radiating  blood- capillaries  and 


FIG.  58. 


Vessels  and  bile-ducts  of  hepatic  lobule  (Cadiat).  a,  intralobular  vein;  6,  inter- 
lobular  veins,  breaking  up  into  intralobular  capillaries :  c,  bile-duct  with  bile- 
capillaries  (shown  only  at  periphery  of  lobule). 

the  bile-passages.  They  are  in  contact  with  one  another,  and 
are  not  intermingled  with  connective  tissue. 

The  intralobular  veins,  the  ultimate  radicles  of  the  hepatic 
veins,  occupy  the  centre  or  axis  of  the  lobules. 

The  intralobular  capillaries  converge  toward  the  intralobular 
vein  from  the  periphery  of  the  lobule,  where  they  are  formed 
by  the  breaking  up  of  the  intfrlobvlor  or  portal  veins;  in 
section  they  appear  as  conspicuous  empty  spaces  or  channels 


138  THE  ALIMENTARY  SYSTEM. 

between  rows  of  liver-cells,  radiating  from  the  intralobular 
vein  in  the  centre.  They  are  so  arranged  that  each  liver-cell 
abuts  on  at  least  one  capillary.  Through  these  capillaries 
the  blood  passes  from  the  portal  vein  to  the  hepatic  vein, 
coming  into  close  relation  with  the  liver-cells  on  the  way. 
The  capillaries  and  the  intralobular  veins  are  lined  with  deli- 
cate endothelium-cells  which  rest  on  the  liver-cells. 

The  bile-passages  are  exceedingly  fine  canals  formed  by 
slight  separations  or  grooves  between  adjacent  liver-cells ; 
short  lateral  blind  branches  sometimes  also  enter  the  bodies 
of  the  cells  themselves.  These  passages  unite  to  form  a  fine 
capillary  network,  which  empties  into  the  bile-ducts  in  the 
interlobular  septa.  Each  bile-capillary  is  separated  from  the 
blood-capillaries  by  at  least  a  portion  of  a  liver-cell.  These 
passages  collect  the  bile  secreted  by  the  liver-cells,  and  though 
atypical  they  are  the  same  in  principle  as  the  lumina  of 
tubular  glands.  In  some  animals,  as  the  frog,  the  tubular 
type  is  more  apparent. 

The  gall-bladder  and  hepatic,  cystic,  and  common  ducts 
are  lined  with  mucous  membrane,  consisting  of  simple  long 
columnar  epithelium  with  intermingled  goblet-cells,  and  sub- 
epithelial  connective  tissue,  in  which  mucous  glands  are 
present.  In  the  gall-bladder  this  coat  forms  intersecting  rugae. 

Beneath  the  mucosa  is  a  fibro-muscular  coat,  composed  of 
firm  fibrous  tissue  containing  involuntary  muscle-cells.  Out- 
side of  this  coat,  over  the  greater  portion  of  the  surface,  is 
an  external  serous  or  peritoneal  covering. 

The  bile  in  the  gall-bladder  is  a  dark  opaque  homogeneous 
secretion,  thick  and  viscid  from  the  presence  of  mucin,  and  is 
devoid  of  formed  elements. 

The  Pancreas. 

The  pancreas  (Fig.  59)  is  a  racemose  gland,  which  secretes 
the  pancreatic  fluid.  It  is  made  up  of  secreting  alveoli  and 
ducts,  supported  in  connective  or  sustentacular  tissue,  which 
divides  it  into  lobes  and  lobules,  and  is  supplied  with  blood- 
vessels, lymphatics,  and  nerves. 

The  sustentacular  or  connective  tissue  consists  of  an  areolar 
or  fibrous  capsule  enveloping  the  gland  ;  of  trabeculse  or 


SECRETING   ALVEOLI.  139 

septa  (interlobular)  of  similar  tissue  which  traverse  the  pan- 
creas and  divide  it  into  lobes  and  lobules ;  and  of  delicate 
connective  tissue  penetrating  between  the  individual  alveoli 
which  make  up  the  lobules,  and  providing  them  with  base- 
ment-membranes. 

The  larger  vessels,  ducts,  and  nerves  are  conveyed  through 
the  organ  in  the  interlobular  connective  tissue. 

The  larger  (or  interlobular)  divisions  of  the  ducts  are  lined 

FIG.  59. 


Portion  of  pancreas  (Bohm  and  Davidoff).    a,  large  duct:    6,  beginning  ducts; 
c,  d,  e,  secreting  alveoli ;  g,  sustentacular  connective  tissue. 

with  simple  columnar  epithelium ;  the  small  ductules  with  flat- 
tened epithelium-cells. 

The  secreting  alveoli  are  rather  tubular  in  form,  of  the 
serous  type,  and  are  lined  with  a  single  layer  of  spheroidal 
or  columnar  glandular  epitheli urn-cells.  The  lumen  of  the 
alveoli  also  sometimes  contains  small  cells,  called  centro-acinal 
cells. 

The  cells  lining  the  alveoli  vary  according  to  the  stage  of 
secretion.  Before  secretion  these  cells  are  distended,  and  the 
zone  toward  the  lumen  is  clear  and  contains  coarse  zymogen- 


140  THE  ALIMENTARY  SYSTEM. 

granules,  while  the  protoplasmic  zone  toward  the  attached 
bases  of  the  cells,  where  the  nuclei  are  situated,  is  dark,  more 
opaque,  and  less  (or  more  finely)  granular.  During  secretion 
the  zymogen-granules  and  clear  material  distending  the  cells 
are  discharged  ;  when  exhausted  by  prolonged  activity  the 
cells  are  thus  left  shrunken,  darker,  opaque,  and  non-granular 
(or  only  finely  granular). 

Bodies  of  Langerhans :  Between  the  lobules  in  places  are 
rounded  vascular  aggregations  of  small  cells,  more  open  and 
less  dense  than  the  secreting  alveoli  which  make  up  the  bulk 
of  the  gland  ;  these  are  called  the  bodies  of  Langerhans,  and 
are  perhaps  imperfectly  developed  lobules,  though  their  nature 
is  not  entirely  understood. 


CHAPTER    XI. 
THE  RESPIRATORY  SYSTEM. 

GENERAL  CONSIDERATIONS. 

The  lungs :  One  function  of  the  lungs,  analogous  to  that  of 
the  alimentary  system,  is  to  furnish  to  the  circulation  material 
(in  this  case  oxygen)  required  in  the  nutrition  of  the  body. 
Their  other  function,  the  excretion  of  carbon  dioxide,  is  a 
glandular  process,  and  in  view  of  it  the  lungs  can  be  regarded 
as  a  gland ;  they  certainly  approach  the  glandular  type  as 
closely  as  does  the  liver. 

The  structure  of  the  lungs  is  strikingly  that  of  racemose 
glands ;  the  main  departure  from  the  ordinary  glandular  type 
is  that  the  substances  interchanged  are  gaseous  rather  than 
liquid  or  solid,  and  the  medium  of  excretion  consists  not  of 
spheroidal  cells,  but  of  squamous  cells  adapted  to  the  ex- 
change of  gases. 

The  analogy  of  the  lungs  to  a  gland  is  increased  if  their 
alimentary  or  oxygen-furnishing  function  be  regarded  as  a 
sort  of  internal  secretory  process,  in  which  the  separated 
product  is  discharged  into  the  blood. 

The  other  portions  of  the  respiratory  apparatus,  the  nose, 
pharynx,  larynx,  trachea,  and  bronchi  (the  ducts  or  air-pas- 
sages of  the  lungs),  and  the  pleura,  for  the  most  part  simply 
serve  tributary  and  subordinate  purposes  to  the  lungs. 

The  Nasal  Fossae. 

The  mucous  membrane  lining  the  nasal  fossae  rests  upon  the 
periosteal  and  perichondrial  coverings  of  the  surrounding 
bones  and  the  hyaline  cartilaginous  septum,  and  is  continuous 
with  the  skin  and  the  mucous  membrane  of  the  nasal  ducts, 
pharynx,  and  Eustachian  tubes.  It  is  composed  of  two  dis- 
tinct areas,  the  respiratory  and  the  olfactory.  The  olfactory 
area  comprises  the  upper  part  of  the  fossaB,  namely,  the  upper 

141 


142  TEE  RESPIRATORY  SYSTEM. 

third  of  the  septum,  the  roof  of  the  nose,  the  superior  and  part 
of  the  middle  turbinated  bone,  and  the  ethmoid  in  front  of 
them.  The  remainder  of  the  nasal  fossae  and  the  accessory 
sinuses  (maxillary,  ethmoidal,  sphenoidal,  frontal)  are  covered 
by  the  respiratory  portion  of  the  mucosa. 

The  respiratory  portion  of  the  nasal  mucous  membrane,  like 
the  air-passages  in  general,  is  lined  with  stratified  ciliated 
epithelium,  among  which  are  occasional  goblet-cells.  The 
epithelium  rests  on  a  firm  tunica  propria,  beneath  which  is  a 
variable  amount  of  loose  submucous  areolar  and  connective 
tissue.  The  submucosa  contains  abundant  and  ample  blood- 
vessels, nodules  and  diffuse  masses  of  lymphoid  tissue,  and 
small  racemose  mucous  glands  with  ducts  lined  by  columnar 
epithelium,  gradually  merging  into  the  ciliated  cells  of  the 
surface.  The  vascularity  of  this  region  explains  the  fre- 
quency of  nosebleed.  Over  the  septum  and  turbinated  bones 
the  mucous  membrane  is  thick,  very  vascular,  and  contains 
large  numbers  of  the  glands ;  in  the  accessory  sinuses  it  is 
thin  and  less  glandular  and  vascular. 

The  olfactory  portion  of  the  nasal  mucous  membrane  con- 
tains the  nerve-terminals  for  the  sense  of  smell.  It  is  thick, 
and  mostly  pigmented,  of  a  yellowish  color.  Its  superficial 
layer  is  composed  of  stratified  columnar  non-ciliated  epithe- 
lium. The  surface-cells  are  of  two  kinds,  sustentacular  and 
olfactory. 

The  sustentacular  or  supporting  cells  are  long  columnar  cells, 
with  deeply  placed  oval  nuclei ;  their  deep  portions  are 
branched  and  irregular,  their  free  extremities  are  granular 
and  exhibit  the  appearance  of  a  superficial  covering  cuticle. 

The  olfactory  cells  are  slender,  elongated,  linear  cells,  with 
large  spherical  nuclei  which  cause  a  marked  bulbous  swelling 
of  the  cell-body.  They  lie  between  the  supporting  cells,  and 
are  a  form  of  neuro-epithelium,  or,  perhaps,  actual  nerve- 
cells.  Their  lower  extremities  are  continuous  with,  or  at  least 
in  intimate  relation  with,  terminal  filaments  of  the  olfactory 
nerve.  Their  prominent  round  nuclei  form  a  zone  in  the 
lower  portion  of  the  epithelial  layer.  The  lowest  epithelium- 
cells  are  spheroidal  and  germinal. 

The  epithelium  rests  upon  a  connective-tissue  layer,  the 
tunica  propria  and  submucosa,  which  contain  the  terminal 


THE  LARYNX.  143 

filaments  into  which  the  olfactory  nerves  divide,  and  large 
numbers  of  small  mucous  glands. 

The  pharynx :  The  upper  portion  of  the  pharynx,  which 
has  been  already  described  (page  124),  belongs  to  the  respira- 
tory tract,  and  is  lined  with  ciliated  epithelium,  while  the 
lower  portion,  lined  with  squamous  epithelium,  pertains  rather 
to  the  alimentary  canal. 

The  Larynx. 

The  larynx  is  a  cartilaginous  box  surmounting  the  trachea 
and  containing  the  vocal  apparatus. 

Its  main  cartilages,  the  thyroid,  cricoid,  and  larger  portions 
of  the  arytenoids,  are  of  the  hyaline  variety,  tending  in  old 
age  to  become  ossified.  The  other  cartilages,  those  of  the  epi- 
glottis, certain  processes  of  the  arytenoids,  the  cornicula 
laryngis,  and  cuneiform  cartilages  (cartilages  of  Santorini  and 
Wrisberg),  are  elastic  cartilage. 

The  ligaments  and  membranes  (thyro-hyoid  and  crico- 
thvroid)  which  complete  the  framework  of  the  larynx  are 
fibro-elastic  structures. 

The  interior  of  the  larynx  is  lined  with  mucous  membrane, 
consisting  of  an  epithelial  layer,  tunica  propria,  and  sub- 
mucous  tissue. 

The  epithelial  lining  of  the  larynx  above  the  ventricles  and 
over  the  true  vocal  cords  consists  of  stratified  squamous 
epithelium,  continuous  with  that  of  the  pharynx  ;  the  ventri- 
cles and  the  portion  of  the  larynx  below  the  vocal  cords  are 
covered  with  stratified  ciliated  epithelium,  like  that  of  the 
trachea. 

The  tunica  propria  is  a  fibrous  membrane,  containing  numer- 
ous elastic  fibres. 

The  submucosa  consists  of  areolar  tissue,  extending  down 
to  the  periehondrial  coverings,  and  containing  the  larger 
blood  and  lymphatic  vessels,  small  racemose  mucous  glands, 
occasional  masses  of  lymphoid  tissue,  and  the  intrinsic  volun- 
tary muscles  of  the  larynx. 

The  epiglottis  contains  a  basis  of  elastic  cartilage  in  its 
centre,  covered  on  each  side  by  submucous  areolar  tissue  and 


144  THE  RESPIRATORY  SYSTEM. 

a  mucosa.  The  mucous  membrane  on  the  anterior  (or  lingual, 
or  upper)  surface  of  the  epiglottis  is  a  continuation  of  that  of 
the  tongue  and  is  very  similar  to  it. 

The  vocal  cords  are  folds  of  the  mucous  membrane,  with 
the  tunica  propria  reinforced  and  strengthened  by  additional 
elastic  fibres. 


The  Trachea. 

The  trachea  is  a  rigid  tube  extending  from  the  larynx  to 
the  upper  part  of  the  chest,  where  it  divides  into  the  two 
bronchi.  Its  walls  are  made  up,  from  within  outward,  of 
mucous  membrane,  submucous  tissue,  cartilage  and  muscle, 
and  fibrous  tissue. 

The  mucous  membrane  of  the  trachea  is  lined  with  stratified 
ciliated  epithelium-cells  (Fig.  14),  among  which  are  occasional 
goblet-cells.  The  tunica  propria  underlying  the  epithelium  is 
a  firm  supporting  connective-tissue  layer ;  its  most  superficial 
layer  forms  a  basement-membrane  for  the  epithelium  ;  below 
this  the  tunic  is  infiltrated  with  numerous  lymphoid  cells, 
and  its  deepest  portion  contains  numerous  longitudinal  elastic 
fibres. 

Outside  the  tunica  propria  is  the  submucosa,  a  layer  of 
areolar  and  elastic  tissue  ;  it  contains  the  alveoli  of  numerous 
small  racemose  mucous  glands,  occasional  lymphoid  tissue,  and 
the  larger  blood  and  lymphatic  vessels. 

Next  outside  the  submucosa  is  a  series  of  incomplete  rings 
or  horseshoe-shaped  bodies  of  hyaline  cartilage,  defective 
posteriorly,  which  makes  up  the  rigid  incollapsible  framework 
of  the  trachea.  The  connective  tissue  on  the  surfaces  of  the 
cartilage  is  condensed  to  form  a  perichondrium. 

The  hiatus  at  the  posterior  part  of  the  cartilages  is  filled  up 
partially  by  fibrous  tissue,  but  chiefly  by  the  trachealis  muscle, 
a  bridge  of  involuntary  muscle  which  connects  the  ends  and 
posterior  surfaces  of  the  cartilages  ;  the  larger  portion  of  this 
muscle  is  arranged  transversely,  but  externally  there  are  a  few 
longitudinal  fibres. 

There  are  some  mucous  glands  located  posterior  or  external 
to  the  trachealis  muscle,  whose  ducts  pierce  the  muscle  and 
find  their  way  to  the  lumen  of  the  trachea. 


THE  LUNGS.  145 

Outside  of  the  cartilaginous  layer  the  trachea  is  surrounded 
by  fibrous  and  areolar  tissue  continuous  with  that  of  the 
adjacent  structures. 

The  Lungs. 

The  lungs  are  made  up  of  air- vesicles  or  alveoli,  the  ulti- 
mate functional  divisions  of  the  organ ;  bronchial  tubes,  the 
air-passages  leading  to  the  air-vesicles ;  connective  sustentacu- 
lar  tissue ;  an  ample  system  of  bloodvessels,  besides  lymph- 
atics and  nerves;  and  a  serous  covering  derived  from  the 
pleura. 

The  lung-substance  is  more  or  less  distinctly  divided  into 
pyramidal  lobules,  consisting  of  the  groups  of  alveoli  cor- 
responding to  terminal  divisions  of  the  bronchi  and  blood- 
vessels ;  the  lobules  are  to  a  greater  or  less  extent  marked  off 
from  one  another  by  septa,  although  closely  packed  together. 

The  connective  tissue  of  the  lung,  its  sustentacular  frame- 
work, may  be  divided  into  the  superficial  investment  of  the 
organ  and  the  interalveolar,  peribronchial,  and  interlobular 
tissues.  The  surface  of  the  lung  is  surrounded  by  elastic  and 
areolar  tissue,  lying  beneath  the  pleura  and  continuous  with 
its  subserous  layer. 

The  free  surface  is  covered  by  the  visceral  portion  of  the 
pleura. 

The  interalveolar  connective  tissueis  a  delicate  tissue,  mostly 
elastic,  between,  surrounding,  and  forming  a  supporting  frame- 
work for  the  air-vesicles ;  it  comprises  the  larger  part  of  the 
pulmonary  connective  tissue,  and  to  it  are  due  the  well-known 
elasticity  and  contractile  tendency  of  the  lungs. 

The  peribronckial  connective  tissue  is  a  firmer  tissue  of  the 
white-fibrous  variety  which  forms  definite  sustentacular  tracts 
accompanying,  supporting,  and  surrounding  in  a  single  sheath 
the  bronchi  and  their  concomitant  bloodvessels  in  all  their 
ramifications  and  subdivisions  throughout  the  lungs. 

The  interlobular  connective  tissue  consists  of  more  or  less 
definite  thin  fibrous  septa  separating  the  lobules  of  the  organ. 

Pigment,  usually  black,  is  often  abundantly  deposited  in 
patches  in  the  interalveolar  and  interlobular  tissue ;  it  con- 
sists of  particles  inspired  into  the  air- vesicles  and  removed 
into  the  interior  by  the  lymphatics. 

10— Hist. 


146 


THE  RESPIRATORY  SYSTEM. 


The  bloodvessels  of  the  lungs  comprise  two  distinct  sets  of 
arteries,  capillaries,  and  veins  :  the  pulmonary  vessels  and  the 
bronchial  vessels. 

The  pulmonary  vessels  are  far  the  larger  of  the  two  sets 
and  carry  out  the  respiratory  function  of  the  lungs.  The 
pulmonary  arteries  convey  the  venous  blood  from  the  right 
ventricle  of  the  heart,  and  break  up  into  capillaries  which 


General  appearance   of  lung  under  low  magnification  (Dunham),    a,  bronchus; 
b,  muscularis  mucosae  of  bronchus:  c,  pulmonary  veins  ;  d,  e,  infundibula. 

surround  the  air-vesicles  in  a  close  mesh  work.  The  blood, 
aerated  and  arterialized  in  these  capillaries,  is  collected  from 
them  and  returned  in  the  pulmonary  veins  to  the  left  auricle. 
The  pulmonary  arteries  and  veins  accompany  the  bronchi 
in  their  course  throughout  the  lungs,  lying  in  the  same 
sustentacnlar  tract  of  peribronchial  connective  tissue,  the 
bronchus  in  the  centre,  a  pulmonary  artery  on  one  side,  and 
a  pulmonary  vein,  larger  and  with  thinner  walls  than  the 


THE  BRONCHI. 


147 


artery,  on  the  other.  The  size  of  the  pulmonary  vessels 
always  corresponds  to  that  of  the  accompanying  bronchus, 
being  not  far  from  equal  to  it. 

The  bronchial  vessels  are  much  smaller  than  the  pulmonary, 
and  serve  for  the  nutrition  of  the  substance  of  the  lung. 
The  bronchial  arteries  are  branches  of  the  aorta.  The  capil- 
laries from  these  arteries  empty  chiefly  into  the  bronchial 
veins,  but  partly  also  into  the  pulmonary  veins.  The  bron- 
chial veins  empty  ultimately  into  the  vena  cava. 

The  bronchial  vessels  lie  in  the  peribronchial  connective 
tissue  and  accompany  the  bronchi  and  pulmonary  vessels  in 
their  ramifications. 

The  lymphatics  of  the  lungs  comprise  small  channels  origin- 

FIG.  61. 


Portion  of  bronchiole  (pig)  in  cross-section  (Schultze).  a,  submucosa;  b,  mus- 
cularis  mucosae ;  c,  tunica  propria ;  d,  epithelium ;  /,  portions  of  neighboring 
air-vesicles. 

atingfrom  stomata  in  the  air- vesicles,  in  the  sustentacular  and 
perivascular  tissue,  and  from  the  pleural  stomata. 

The  nerves  of  the  lungs  are  small  branches  lying  in  the 
peribronchial  tissue. 

The  bronchi  are  continuations  of  the  trachea,  and  within 
the  lung  divide  and  subdivide  dichotomously  down  to  the 
terminal  bronchioles  (Fig.  61).  They  are  the  air-passages  to 


148  THE  RESPIRATORY  SYSTEM. 

the  ultimate  alveoli  of  the  lungs,  and  are  analogous  to  the 
ducts  of  glands.  They  are  surrounded  by  a  considerable 
amount  of  firm  fibrous  connective  tissue,  the  peribronchial 
tissue ;  each  bronchus  is  accompanied  in  the  same  peribron- 
chial sheath  by  correspondingly  large  pulmonary  vessels,  the 
artery  on  one  side,  the  vein  on  the  other,  and  by  the  smaller 
bronchial  vessels  and  nerves,  usually  a  bronchial  artery,  vein, 
and  nerve  being  on  each  side  of  the  bronchus. 

The  structure  of  the  bronchi  gradually  changes  as  they  vary 
in  size.  At  the  beginning  they  are  about  the  same  in  struct- 
ure as  the  trachea. 

The  medium-sized  bronchi  are  made  up,  from  within  out- 
ward, of  an  epithelial  layer,  a  tunica  propria,  muscularis 
mucosse,  and  a  submucosa,  which  contains  plates  of  cartilage, 
mucous  glands,  and  lymphoid  tissue,  and  extends  to  the  peri- 
bronchial  tissue. 

The  bronchi  are  lined  with  stratified  ciliated,  epithelium,  un- 
derlying which  is  the  tunica  propria,  consisting  largely  of 
elastic  tissue.  These  two  layers  are  thrown  into  longitudinal 
folds. 

The  muscularis  mucosce  is  a  thin  but  well-marked  layer  or 
ring  of  involuntary  muscle,  arranged  circularly  ;  it  separates 
the  tunica  propria  from  the  submucosa,  and  is  not  included 
in  the  longitudinal  folds  of  the  mucosa. 

The  submucosa  consists  of  areolar  tissue,  merging  into  the 
firmer  peribronchial  connective  tissue.  It  contains  small 
racemose  mucous  glands,  whose  ducts  discharge  on  the  epithelial 
surface;  occasional  nodules  of  lymphoid  tissue;  and  unequal 
curved  plates  of  hyaline  cartilage,  the  representatives  of  the 
tracheal  rings,  which  in  cross-sections  appear  as  arcs  incom- 
pletely surrounding  the  bronchi. 

Terminal  bronchioles  :  As  the  bronchi  decrease  in  size  the 
cartilaginous  plates  diminish  and  finally  disappear  entirely  ; 
the  stratified  ciliated  epithelium  becomes  reduced  to  a  single 
layer  of  ciliated  cells,  and  still  later  to  a  layer  of  low  columnar 
non-ciliated  cells;  the  connective-tissue  layers  become  dimin- 
ished in  thickness,  and  the  peribronchial  tissue  and  mucous 
glands  disappear.  Thus,  the  terminal  bronchioles  are  lined 
with  a  single  layer  of  low  columnar  non-ciliated  or  flattened 
polygonal  epithelium-cells,  a  slight  amount  of  fibro-elastic 


THE  AIR-VESICLES.  149 

connective  tissue,  and  a  thinned  and  interrupted  muscularis 
mucosse. 

The  infimdibula  :  At  their  termination  the  bronchioles  open 
into  clusters  of  large  elliptical  cavities,  called  infundibula,  the 

/ 
FIG.  62. 


Diagram  of  air-vesicles  and  termination  of  bronchi  (Miller).  B,  terminal  bronchi- 
ole (the  line  leads  from  a  terminal  artery);  A,  P,  alveolar  passages;  S,  infundi- 
bulum;  C,  air-vesicle ;  T,  beginning  vein. 

walls  of  which  are  beset  with  air-vesicles.  These  infundi- 
bula branch  off  from  the  sides  and  ends  of  the  final  portions 
of  the  bronchioles,  which  are  here  somewhat  expanded  and 
lined  with  flattened  polygonal  epithelium-cells,  and  which  are 
often  called  alveolar  passages. 

Each  infundibulum  is  a  blind  elliptical  sac,  opening  at  one 
point  into  an  alveolar  passage,  and  with  its  walls  formed 
entirely  of  air-vesicles. 

The  air-vesicles  (air-sacs,  air-cells,  or  alveoli)  are  small 
hemispherical  recesses  forming  the  walls  of  the  infundibula 
and  opening  into  the  cavity  of  the  latter.  They  make  up  the 
great  bulk  of  the  lung-substance,  and  are  the  ultimate  June- 


150  THE  RESPIRATORY  SYSTEM. 

tional  divisions  of  the  lungs,  where  the  admission  of  oxygen 
into  and  the  expulsion  of  carbon  dioxide  from  the  blood  take 
place.  They  are  lined  with  a  single  layer  of  large  polygonal 
squamous  epithelium-cells,  at  the  junction  of  which  appear 
occasional  small  intervals  or  stomata  opening  into  lymph- 
passages.  Among  the  squamous  cells  lining  the  vesicles  occur 
here  and  there  small  spheroidal  cells  ;  in  the  foetal  lung,  before 
it  is  expanded  with  air,  the  cells  lining  the  air-vesicles  are  all 
spheroidal. 

Underneath  the  epithelial  lining  is  a  thin  network  of  elastic 
tissue  (the  interalveolar  connective  tissue),  which  forms  the 
framework  and  support  for  the  vesicles.  The  walls  of  the 
alveoli  also  contain  a  close  meshwrork  of  blood-capillaries 
derived  from  the  pulmonary  artery,  in  close  relation  with  the 
squamous  lining  of  the  vesicles,  thus  affording  favorable  con- 
ditions for  the  exchange  of  gases  between  the  venous  blood 
and  the  air  in  the  alveoli.  Adjacent  air- vesicles  are  separated 
from  each  other  only  by  thin  septa,  each  of  which  contains 
but  a  single  set  of  capillaries,  the  loops  of  which  lie  in  relation 
with  the  epithelial  lining  on  both  sides. 

The  pleura  is  a  serous  sac,  the  parietal  portion  of  which 
lines  the  thoracic  wall,  and  whose  visceral  portion  forms  a 
covering  for  the  lung.  It  facilitates  the  movements  of  the 
lungs  over  the  opposing  surfaces.  In  structure  it  is  a  serous 
membrane,  consisting  of  a  fibrous  stratum  covered  with  poly- 
gonal endothelium-cells  on  the  surface.  Beneath  it  is  the  sub- 
serous  or  subpleural  areolar  tissue,  which  in  the  visceral 
portion  of  the  sac  is  continuous  with  the  superficial  connec- 
tive tissue  of  the  lung. 


CHAPTER    XII. 


FIG.  63. 


THE  SKIN. 

THE  skin  serves  integumentary  and  protective  purposes,  is 
an  important  excretory  organ,  is  the  seat  of  sensory  terminals, 
and  possesses  other  functions.  It  consists  of  two  parts,  a 
thin  outer  epithelial  layer,  the  epidermis  or  cuticle,  and  a 
thicker,  lower  connective-tissue  layer,  the  cutis  vera,  or  corium. 
Beneath  it  is  a  variable  layer  of  subcutaneous  tissue.  The 
skin  contains  numerous  glands  of  two  kinds,  sudoriparous 
and  sebaceous,  and  also  the  hairs  and  nails;  these  are  all 
derived  from,  or  modifications  of,  the  epidermis. 

The  epidermis,  the  thinner  outer  layer  of  the  skin,  consists 
of  stratified  squamous  epithelium,  and  is  of  epiblastic  origin. 
It  varies  in  thickness  and  the 
development  of  its  parts  in 
different  situations.  It  is 
divisible,  in  the  first  place,  into 
two  sharply  distinct  layers,  an 
outer,  hard,  horny,  layer,  and 
a  lower,  soft  protoplasmic 
layer,  the  "  rete  mucosum." 
Each  of  these  is  again  divisi- 
ble into  other  strata,  which 
are,  from  the  surface  down- 
ward, the  stratum  corneum 
and  stratum  lucidum,  making 
up  the  horny  portion,  the 
stratum  granulosum  and  stra- 
tum Malpighii,  making  up  the 
rete  mucosum.  In  addition, 
the  lowermost  layer  of  (co- 
lumnar") cells  in  the  Mai-  Section  of  skin,  showing  sweat-gland,  a, 

,7  stratum  corneum;   6,  rete  mucosum; 

pighian    Stratum  IS  almost  dlS-        c,  corium ;  d,  subcutaneous  tissue. 

tinct   enough    to   be  differen- 
tiated as  a  special  layer.    These  layers  may  be  exhibited  thus  : 

151 


152  THE  SKIN. 

,.      .  -,  f  Stratum  corneum. 

Horny  portion  of  epidermis  j  Stn!t/um  lucidum. 

(    Stratum  granulosum. 
Retemaconim |   Stratum  Malpighii. 

Of  these  layers  the  strata  corneum  and  Malpighii  are  the 
thickest,  most  prominent,  and  always  present;  the  strata 
lucidum  and  granulosum  are  much  thinner,  less  conspicuous, 
and  where  the  epidermis  is  thin  may  be  quite  indistinguish- 
able. There  are  no  bloodvessels  or  capillaries  in  the  epider- 
mis, but  lymph  is  probably  able  to  percolate  between  the  cells. 

The  stratum  Malpig-hii  (or  stratum  germinativum)  consists 
of  about  ten  to  twenty-five  layers  of  .deeply  staining  sphe- 
roidal epithelium-cells  resting  on  the  corium.  Into  this 
stratum  project  the  papillae  which  stud  the  surface  of  the 
corium,  the  intervals  between  the  papillse  being  filled  with 
epithelial  cells.  The  lowermost  cells  of  the  Malpighian 
stratum  form  a  single  layer  of  tall  columnar  cells  arranged 
perpendicular  to  the  surface  of  the  papilla  and  corium  ;  this 
layer  forms  a  quite  distinct  stratum.  The  other  cells  of  the 
Malpighian  layer,  larger  than  the  columnar  cells,  are  spheroi- 
dal in  shape,  or  polyhedral  from  mutual  pressure,  becoming 
somewhat  flattened  above.  They  are  disposed  irregularly,  not 
in  uniform  layers,  and  have  characteristic  "  vesiculated  nuclei " ; 
that  is,  their  nuclei  are  surrounded  by  or  seem  to  lie  in  a  clear 
vesicular  space.  The  surfaces  of  these  cells  are  closely  beset 
with  ridges,  or  "  intercellular  bridges,"  causing  the  cells  to 
appear  in  cross-section  as  if  studded  with  projecting  prickles 
or  spines,  whence  they  are  often  called  prickle- cells.  The 
ridges  of  adjacent  cells  unite  edge  to  edge,  and  the  minute 
communicating  channels  left  between  them  probably  enable 
lymph  to  pass  between  these  cells  for  the  nourishment  of  the 
non-vascular  epidermis.  The  cells  of  the  deeper  portion  of 
the  stratum  Malpighii  contain  pigment,  which  gives  color  to 
the  skin,  especially  in  freckles  and  dark-skinned  races.  The 
Malpighian  layer  contains  terminal  nerve-fibrils  and  tactile 
cells. 

The  stratum  granulosum  rests  upon  the  stratum  Malpighii, 
the  two  merging  together  without  sharp  dividing-lines.  It  is 
not  always  very  distinct,  but  in  thick  epidermis  it  appears 


SUBCUTANEOUS  TISSUE.  153 

very  prominently  as  consisting  of  three  or  four  layers  of 
flattened,  lenticular,  or  (in  cross-section)  fusiform  cells,  which 
are  dark,  stain  very  deeply,  and  contain  coarse  granules  of  a 
substance  called  eleidin,  supposed  to  be  a  precursor  of  the 
horny  substance  of  the  more  superficial  cells  of  the  epidermis. 

The  stratum  lucidum  is  a  thin,  translucent  layer  of  horny, 
flattened  cells,  lying  on  the  stratum  granulosum,  and  forming 
the  lowest  layer  of  the  horny  portion  of  the  epidermis.  It 
is  often  indistinct. 

The  stratum  corneum  consists  of  numerous  layers  of  flat, 
squamous  cells,  and  forms  the  thick,  outer,  horny  layer  of  the 
epidermis.  The  cells  consist  of  a  hard,  horny  substance,  or 
keratin,  into  which  the  protoplasm  of  the  underlying  cells  has 
become  converted.  There  is  practically  no  vitality  left  in 
these  cells,  but  they  are  well  adapted  to  protective  purposes. 
In  vertical  section  the  cells  appear  as  a  succession  of  wavy 
lines,  with  occasional  indistinct  traces  of  the  degenerated 
nuclei. 

The  corium,  cutis  vera,  or  dennis,  is  the  connective-tissue 
portion  of  the  skin,  of  mesoblastic  derivation.  It  is  a  firm 
fibrous  layer,  corresponding  to  the  tunica  propria  of  mucous 
membranes,  and  is  thicker  than  the  epidermis ;  to  it  the  firm- 
ness of  the  skin  is  due.  It  consists  of  an  interlacing  network 
of  white  and  some  elastic  fibres,  among  which  are  scattered 
fusiform  connective-tissue  cells ;  mingled  with  these  are  numer- 
ous capillaries,  small  lymph-vessels,  and  nervous  elements. 

The  upper  surface  of  the  corium  presents  numerous  oval 
papiUce  projecting  upward  into  the  stratum  Malpighii,  which 
fills  the  intervals  between  them.  Some  of  the  papillae  are 
occupied  by  capillary  loops,  others  by  tactile  nerve-terminals. 
In  some  situations  the  papilla?  are  closely  crowded,  in  others 
more  sparsely.  The  arrangement  of  the  papilla?  gives  rise  to 
the  lines  of  the  palm  and  sole,  and  to  other  superficial  mark- 
ings elsewhere. 

The  lower  surface  of  the  corium  is  plane  and  merges  into 
the  subcutaneous  tissue. 

The  subcutaneous  tissue  (or  superficial  fascia)  is  a  layer  of 
loose  areolar  and  adipose  tissue  which  underlies  the  corium 
and  extends  to  the  subjacent  structures.  It  varies  in  thick- 
ness in  different  parts  of  the  body,  and  corresponds  to  the 


154  THE  SKIN. 

submucous  layer  of  mucous  membranes.  This  tissue  contains 
the  larger  vascular  and  nervous  branches,  and  Pacinian  cor- 
puscles ;  the  hair-follicles  and  sweat-glands  project  down  into 
it.  Next  to  the  corium  the  subcutaneous  tissue  is  mostly 
loose  and  areolar,  while  deeper  is  a  variable  and  often  thick 
layer  of  fatty  tissue,  the  pannieulus  adiposus. 

The  sudoriparous  or  sweat-glands  (Fig.  63)  occur  in  great 
abundance  over  the  entire  skin,  and  are  derived  from  down- 
growths  of  the  epidermic  epithelium.  They  are  simple  tubu- 
lar glands  of  the  serous  type,  consisting  of  single  tubes  lined 
by  epithelium  resting  on  a  basement-membrane,  and  sup- 
ported in  the  surrounding  connective  tissue.  They  extend 
from  the  surface  downward  into  the  subcutaneous  tissue  or 
lowest  part  of  the  corium,  and  their  deeper  portions  are  much 
convoluted.  They  consist  of  two  parts,  a  secreting  portion 
and  an  outlet-duct.  The  secreting  portion  consists  of  the 
lower  part  of  the  tube,  sometimes  somewhat  branched,  and  is 
coiled  and  convoluted  into  a  rounded  nodule  situated  in  the 
subcutaneous  tissue.  Its  calibre  is  larger  than  that  of  the 
outlet  portion,  and  it  is  lined  with  a  layer  of  columnar 
epithelium.  Between  the  epithelium-cells  and  their  basement- 
membrane  occur  scattered  involuntary  muscle-cells. 

The  outlet-duet  is  a  narrow  tube  of  uniform  size  lined  with 
two  layers  of  spheroidal  epithelium-cells.  After  leaving  the 
convoluted  secretory  portion  of  the  tube  it  pursues  a  straight 
or  slightly  wavy  course  to  the  epidermis,  which  it  enters  be- 
tween the  papillae.  In  the  stratum  Malpighii  its  lining  is 
formed  by  the  cells  of  that  layer.  Through  the  stratum 
corneum  the  duct  passes  to  the  surface  in  a  spiral  or  cork- 
screw course  through  the  horny  substance.  The  ceruminous 
glands  of  the  ear  are  modified  sweat-glands. 

The  hairs  occur  in  the  skin  over  nearly  the  entire  surface, 
being  especially  numerous  and  well  developed  in  certain 
regions.  They  are  composed  of  horny  cells  derived  from  the 
epidermis.  The  lower  end  of  each  hair  exhibits  a  rounded 
enlargement,  the  bulb. 

The  root  of  the  hairs,  the  portion  imbedded  in  the  skin, 
extends  into  the  subcutaneous  tissue,  and  is  supported  in  and 
grows  from  a  sheath,  the  hair-follicle,  formed  by  a  downgrowth 
of  the  epidermis  and  corium. 


HAIR-FOLLICLES. 


155 


A  human  hair  is  round  or  flat- 
tened an.i  made  up  of  three  parts, 
a  cuticle,  a  cortex,  and  a  medulla. 

The  cuticle  is  a  thin  outer  cov- 
ering composed  of  thin  non- 
nucleated  horny  plates  or  cells, 
imbricated  or  overlapping  ;  their 
edges  form  irregular  transverse 
markings  on  the  surface  of  the 
hair. 

The  cortex,,  making  up  the 
bulk  of  hair,  consists  of  slender, 
elongated,  fusiform,  horny  nu- 
cleated cells,  arranged  longi- 
tudinally and  closely  packed  and 
cemented  together. 

The  medulla  is  not  always 
continuous  or  present ;  it  con- 
sists of  nucleated  polyhedral  cells 
loosely  aggregated  in  the  axis  of 
the  hair;  these  cells  often  con- 
tain air,  giving  them  an  opaque 
appearance. 

Hairs  often  contain  pigment, 
deposited  in  the  cortex ;  to  this 
pigment  and  the  air  in  the  med- 
ulla the  color  of  hair  is  due. 

The  hair-follicles  (Fig.  64), 
which  support  the  hairs  and  pro- 
vide for  their  growth,  are  sheaths 
formed  by  downward  projections 
of  the  epidermis  and  corial  tis- 
sue. They  lie  perpendicular  or 
oblique  to  the  surface,  and  into 
their  upper  half  the  sebaceous 
glands  open.  A  small  band  of 
involuntary  muscle  extends  from 
the  lower  part  of  the  follicle  to 
the  corium  across  the  obtuse- 
angled  side,  forming  the  erector 


FIG.  64. 


ep 


Longitudinal  section  of  hair-follicle 
(Biesiadecki).  r.  bulb  of  hair ;  d,  e, 
sheaths  derived  from  the  corium  ; 
/,  outer  root-sheath  ;  <7,  inner  root- 
sheath  ;  h,  hair ;  k,  medulla  of  hair  ; 
n,  erector  pili  muscle  ;  p,  papilla  of 
hair  :  .*.  rete  mucosum  ;  ep,  stratum 
corneum ;  t,  sebaceous  gland. 


156  THE  SKIN. 

pili  muscles,  which  elevate  the  hairs  and  cause  projections  of  the 
skin  at  their  bases  (cutis  anserina).  The  hair-follicles  consist 
of  two  parts — an  outer  fibrous  sheath  derived  from  the  coriuni, 
and  an  inner  epithelial  portion  continuous  with  the  epidermis. 

The  outer  fibrous  sheath  is  a  supporting  investment  of  fibrous 
tissue,  longitudinally  and  circularly  arranged,  continuous  with 
the  coriuni ;  its  innermost  layer,  next  to  the  epidermic  sheath, 
is  a  translucent  basement-membrane,  the  hyaline  layer.  At 
the  lower  end  of  the  follicle  the  corial  tissue  sends  a  cellular 
and  vascular  projection,  the  papilla,  into  the  hair-bulb. 

The  inner  and  more  conspicuous  epithelial  portion  of  the 
hair-follicle  is  formed  by  a  dipping  clown  of  the  epidermis 
about  the  root  of  the  hair.  It  corresponds  mainly  to  the  rete 
mucosum,  the  stratum  corneum  extending  inward  only  a  short 
distance  near  the  mouth  of  the  follicle.  The  epidermic  por- 
tion of  the  follicle  is  usually  described  as  consisting  of  two 
parts,  an  outer  root- sheath  and  an  inner  root-sheath. 

The  outer  root-sheath  is  a  continuation  of  the  stratum  Mal- 
pighii,  and  consists  of  several  layers  of  cells  similar  to  those 
of  that  layer  in  the  epidermis.  The  outermost  layer  of  col- 
umnar cells,  resting  on  the  hyaline  membrane,  is  very  well 
marked.  Alongside  the  expansion  of  the  bulb  of  the  hair 
the  outer  or  Malpighian  sheath  becomes  thinner.  At  the 
lower  portion  of  the  bulb  this  sheath  curves  around,  upward, 
and  inward,  resting  on  the  papilla,  and  becomes  continuous 
with  the  cells  of  which  the  hair  is  composed,  which  are  thus 
formed  by  gradual  transition  from  the  Malpighian  cells ;  the 
innermost  cells  in  this  situation,  next  the  papilla,  become 
cuboidal  and  merge  into  the  medulla  of  the  hair,  while  the 
outer  cells  become  gradually  converted  into  the  elongated 
horny  cells  of  the  hair-cortex. 

The  inner  root-sheath  lies  between  the  hair  and  outer  sheath 
along  the  lower  half  of  the  follicle ;  above  it  changes  to  a 
homogeneous  sheath  which  fades  gradually  away,  while  be- 
low, in  the  lower  part  of  the  bulb,  the  inner  sheath  is  gradu- 
ally lost.  It  consists  of  three  layers — Henle's  layer,  Hux- 
ley's layer,  and  the  cuticular  layer,  from  without  inward. 

The  layer  of  Henle  is  a  thin,  translucent  stratum  composed 
of  a  single  layer  of  flattened  cells,  next  to  the  Malpighian 
sheath.  Next  within  is  the  layer  of  Huxley,  consisting  of 


THE  NAILS.  157 

three  or  four  strata  of  polyhedral  cells,  which  stain  deeply 
and  are  perhaps  analogous  to  those  of  the  stratum  granu- 
losum.  The  innermost  layer  is  the  cuticular  layer,  composed 
of  a  stratum  of  overlapping  cells  lying  in  close  association 
with  the  cuticle  of  the  hair. 

The  sebaceous  glands  are  oval  glandular  saccules  lying 
alongside  the  upper  part  of  the  hair-follicles,  into  which  they 
empty.  Some  are  simple  or  single ;  others  divided  into  a  few 
saccules.  Their  secretion,  the  sebum,  is  of  a  fatty  nature,  and 
serves  to  oil  and  soften  the  skin  and  hair.  In  some  situations, 
as  the  labia  minora  and  glans  penis,  they  occur  unassociated 
with  hairs  and  open  directly  on  the  surface.  Sebaceous  glands 
are  supported  in  the  surrounding  fibrous  tissue,  have  short 
outlet-ducts,  and  are  solid  masses  of  cells  without  open  lumina. 
The  peripheral  cells  are  smaller,  spheroidal,  and  darker  col- 
ored ;  the  cells  in  the  centre  of  the  glands  are  much  larger 
and  clearer,  being  infiltrated  with  numerous  droplets  of  fat. 
All  the  cells  have  well-marked  nuclei. 

The  nails  are  modifications  of  the  epidermis,  consisting 
essentially  of  a  much-thickened  stratum  lucidum.  The  lay- 
ers on  which  the  nail  rests  and  to  which  it  is  attached  form  its 
bed.  The  nail  grows  only  from  the  posterior  or  proximal 
part  of  the  bed,  or  the  matrix,  the  pale,  visible  convex  por- 
tion of  which  is  the  lunula.  The  posterior  edge  of  the  nail, 
its  root,  rests  in  a  groove  formed  by  a  fold  of  rete  mucosum. 
The  corium  beneath  the  nail  exhibits  the  usual  fibrous  struct- 
ure ;  its  surface  anterior  to  or  beyond  the  matrix  forms  longi- 
tudinal ridges,  representing  papillae ;  over  the  matrix  are 
papillae  of  the  ordinary  form.  On  the  corium  rests  a  stratum 
Malpighii  of  the  usual  type,  filling  the  depressions  between 
the  ridges,  and  overlaid  by  a  stratum  granulosum.  Upon  this 
is  the  body  of  the  nail  (corpus  unguium),  a  thick,  horny  layer 
derived  from  cells  which  have  been  transformed  into  keratin  ; 
it  represents  a  highly  developed  stratum  lucidum,  and  is 
formed  only  over  the  matrix,  where  continual  growth  keeps 
forcing  it  onward  over  the  remainder  of  its  bed.  There  is  no 
stratum  corneum  over  the  nails. 


CHAPTER    XIII. 
THE  URINARY   ORGANS. 

THE  action  of  the  urinary  organs  is  excretory,  serving  to 
remove  from  the  blood  waste  katabolic  products  and  super- 
fluous ingested  substances.  The  urinary  apparatus  consists 
of  the  kidneys,  ureters,  bladder,  and  urethra,  the  latter  in  the 
male  being  also  utilized  in  the  genital  function. 

The  Kidneys. 

General  structure :  The  kidneys  are  compound  tubular 
glands.  They  exhibit  two  parts,  the  parenchyma  or  secreting 
portion,  and  the  sinus,  a  cavity  containing  the  calices  of  the 
ureter  in  which  the  urine  collects  and  is  discharged  into  the 
ureter,  which  is  the  outlet-duct  of  the  kidney.  The  sinus  is 
situated  within  the  kidney,  of  which  the  concave  inner  mar- 
gin constitutes  the  hilum  of  the  organ,  where  the  ureter,  renal 
artery,  vein,  lymphatics,  and  nerves  enter.  The  renal  paren- 
chyma is  arranged  in  a  radiating  manner  about  the  sinus,  and 
consists  of  two  well-marked  zones,  an  outer  or  cortex,  and  an 
inner  or  medulla. 

The  structural  elements  of  the  kidney  are  the  uriniferotis 
tubules  (beginning  with  prominent  rounded  bodies,  the  Mal- 
pighian  bodies),  bloodvessels,  and  sustentacular  connective 
tissue,  besides  inconspicuous  lymphatics  and  nerves  and  the 
lining  of  the  sinus.  The  kidneys,  being  derived  from  the 
foetal  Wolffian  body,  are  developed  from  the  mesoblast,  thus 
forming  a  notable  exception  to  the  usual  epiblastic  origin  of 
epithelium. 

The  medulla  of  the  kidney  is  composed  of  a  number  (eight 
to  eighteen)  of  conical  bodies,  called  the  pyramids  of  Mal- 
pighi.  These  radiate  about  and  from  the  renal  sinus,  with 
their  bases  outward,  resting  against  the  cortex,  and  their 
apices  pointing  in  toward  the  renal  pelvis  (of  the  ureter), 

158 


MEDULLA    OF  THE  KIDNEY. 


159 


into  the  cavities  of  the  subdivisions  of  which  (calices)  their 
apices  project  as  papillae.  The  pyramids  (or  the  renal  medulla) 
have  a  light- colored,  shining,  striated  appearance,  the  striae 
being  radiating  or  nearly  parallel.  Two  zones  in  the  medulla 
are  sometimes  distinguished,  an  outer  "boundary  layer7'  and 


FIG.  65. 


Lobe 


Diagrammatic  sketch  of  structure  of  kidney  (Dunham),    a,  6,  epithelium  lining 
the  calix  ;  c,  column  of  Berlin ;  d,  interlobular  artery;  e,  arcuate  artery. 

an  inner  "  papillary  layer."     The  substance  of  the  pyramids 

consists  chiefly  of  straight  urinary  tubules  converging  to  the 

apices ;  these  produce  the  striated  appearance  of  the  pyramids. 

The  pyramids  are  often   separated  from   one  another  by 


160  THE   URINARY  ORGANS. 

walls  or  processes  of  the  cortical  substance  dipping  down 
between  them,  called  the  columnar  Bertini;  in  these  columns 
the  bloodvessels  pass  into  the  substance  of  the  kidney. 

The  adult  human  kidney  is  not  normally  divided  into 
lobes ;  but  in  some  mammals  and  in  early  human  life  the 
kidney  is  lobed,  each  Malpighian  pyramid  with  the  adjacent 
cortical  substance  forming  a  distinct  lobe  separated  from  other 
lobes  by  clefts  in  the  renal  substance. 

The  cortex  of  the  kidney  is  a  dark-red  granular  zone,  much 
narrower  than  the  medullary  region,  and  forming  the  periph- 
ery, just  underneath  the  capsule.  It  also  sends  processes 
down  between  the  Malpighian  pyramids,  the  columnar  Bertini 
mentioned  above.  The  substance  of  the  cortex  is  divided 
into  the  pyramids  of  Ferrein  and  the  interpyramidal  regions, 
which  alternate  with  one  another. 

The  pyramids  of  Ferrein,  or  medullary  rays,  or  cortical 
pyramids,  are  narrow  bundles  or  sheaves  of  straight  tubules 
which  radiate  from  the  outer  boundary  of  the  Malpighian 
pyramids  through  the  cortex  nearly  to  the  periphery.  These 
cortical  pyramids  consist  of  straight  portions  of  the  uriuifer- 
ous  tubules,  which  are  continuations  of  the  radiating  tubules 
of  the  Malpighian  pyramids,  each  of  the  latter  giving  off  a 
number  of  pyramids  of  Ferrein  from  its  base.  The  tubules 
in  the  centre  are  longer  than  those  on  the  outside  of  each 
pyramid  of  Ferrein,  giving  it  the  shape  of  a  cone  with  a 
narrow  base. 

The  intervals  between  the  cortical  pyramids  are  occupied 
by  the  interpyramidal  substance  (or  labyrinth)  of  the  cortex. 
This  consists  of  the  coiled  and  irregular  portions  of  the 
uriniferous  tubules,  twisting  in  all  directions,  studded  and 
intermingled  with  the  numerous  prominent  round  Malpighian 
bodies,  which  give  the  cortex  its  granular  character. 

The  interpyramidal  cortical  regions  comprise  the  active 
secretory  parts  of  the  kidney;  the  pyramids  of  Ferrein  and 
Malpighi  simply  contain  conducting  tubules. 

The  sustentacular  connective  tissue  of  the  kidney  consists 
of  the  capsule,  the  intertubular  or  interstitial  tissue,  the  peri- 
vascular  tissue,  and  the  connective  tissue  lining  the  wall  of 
the  renal  sinus  and  continuous  with  the  pelvis  (ureter). 

The  capsule  is  a  firm  fibrous   membrane  enveloping  the 


SUSTENTACULAR   CONNECTIVE  TISSUE. 


161 


gland  ;  it  is  connected  with  the  delicate  intertubular  tissue 
of  the  interior ;  but  as  it  does  not  send  any  firm  trabeculae 

FIG.  66. 


Diagrammatic  representation  of  uriniferous  tubules  (Klein).  A,  cortex  of  kidney; 
B,  boundary  zone,  and  C,  papillary  portion  of  Malpighian  pyramid  ;  a,  subcap- 
sular  portion,  and  a',  inner  portion  of  cortex  destitute  of  Malpighian  bodies; 
],  Malpighian  body,  capsule  of  Bowman,  and  glomerulus;  2,  neck  ;  3,  proximal 
convoluted  tubule;  4,  spiral  tubule;  5,  descending  limb  of  Henle's  loop; 
6,  Henle's  loop;  7,  8,  9,  ascending  limb  of  Henle's  loop;  10,  irregular  tubule; 
11,  distal  convoluted  tubule;  12,  curved  tubule;  13, 14,  collecting  tubule. 


11  — Hist. 


162  THE   URINARY  ORGANS. 

into  the  gland  it  can  normally  be  easily  stripped  off  from  the 
surface. 

The  connective  tissue  permeating  the  renal  parenchyma 
(the  intertubular  or  interstitial  tissue)  is  a  delicate  tissue,  very 
small  in  quantity,  penetrating  between  and  supporting  the 
uriniferous  tubules  and  vascular  channels ;  it  consists  chiefly 
of  the  basement-membranes  on  which  the  tubules  rest.  Some 
connective  tissue  also  accompanies  the  vessels  entering  at  the 
hilurn,  and  in  and  beneath  the  lining  of  the  renal  sinus  are 
considerable  quantities  of  fibrous,  areolar,  and  adipose  tissue. 

The  uriniferous  tubules  (Fig.  66)  are  the  secreting  or  gland- 
ular elements  of  the  kidney.  They  consist  of  long  tubes, 
which  (except  the  larger  collecting- ducts)  are  single  and  un- 
branched.  They  are  lined  with  a  single  layer  of  epithelium- 
cells  resting  on  a  basement-membrane,  and  in  different  parts 
of  their  course  exhibit  different  divisions  varying  in  arrange- 
ment, form,  and  structure.  The  parts  into  which  the  tubules 
are  divided  are,  in  their  order,  as  follows  :  Malpighian  body  ; 
neck ;  proximal  or  first  convoluted  tubule ;  spiral  tubule ; 
the  loop  of  Henle  (consisting  of  a  descending  limb  and  ascend- 
ing limb) ;  irregular  tubule ;  distal  or  second  convoluted 
tubule ;  curved  or  arched  tubule ;  straight  collecting  tubule, 
and  tube  of  Bellini. 

The  Malpighian  body  is  a  hollow  spherical  structure  or  ex- 
panded sac  forming  the  beginning  of  each  uriniferous  tubule. 
Its  wall  is  formed  by  a  membrane  called  the  capsule  of  Bow- 
man, and  into  its  cavity,  but  covered  by  its  epithelium,  pro- 
jects a  tuft  of  capillary  bloodvessels  called  the  glomerulus. 

The  capsule  of  Bowman  consists  of  a  single  layer  of  squam- 
ous  epithelium  resting  on  a  basement-membrane.  It  forms  a 
hollow  spherical  sac,  the  cavity  of  which  at  one  point  opens 
into  the  proximal  convoluted  tubule  through  a  small  neck. 
The  layer  of  squamous  epithelium  is  invaginated  into  the 
cavity  so  as  to  form  a  complete  covering  for  the  glomerulus 
(Fig.  67). 

The  glomerulus  is  a  tuft  of  capillaries  coiled  into  a  spherical 
mass  nearly  filling  the  interior  of  the  Malpighian  body. 

The  capillaries  arise  from  a  single  afferent  vessel,  and  unite 
to  form  a  single  slightly  smaller  efferent  vessel;  these  two  ves- 
sels enter  and  leave  the  glomerulus  together,  forming  a  sort 


MALPIGHIAN  BODIES. 


163 


of  stalk  for  the  tuft,  at  a  point  opposite  the  neck  or  junction 
of  the  body  with  the  uriniferous  tubule. 

The  surface  of  the  glomerulus  is  covered  with  a  layer  of 
squamous  epithelium  ("tuft-cells")?  dipping  down  into  the 
depressions  between  the  capillary-loops ;  this  epithelium  is  a 

FIG.  67. 


Sketch  of  Malpighian  body  (Dunham),  a,  interlobular  artery;  6,  afferent  vessel: 
c,  capillary ;  d,  capsule  of  Bowman ;  e,  cavity  of  the  capsule ;  /,  beginning  of 
proximal  convoluted  tubule ;  g,  portions  of  convoluted  tubules. 

reflection  of  that  lining  the  capsule  of  Bowman,  with  which 
it  is  continuous  at  the  stalk  of  the  glomerulus. 

Thus  the  glomerulus  is  "outside"  the  capsule  of  Bow- 
man just  as  the  heart  is  outside  the  cavity  of  the  pericardium. 

Malpighian   bodies — arrangement  and  function:    The  Mai- 


164  THE   URINARY  ORGANS. 

pighian  bodies  are  all  situated  in  the  interpyraraidal  portions 
of  the  cortex,  which  they  stud  as  prominent  granular  points. 
The  arrangement  of  the  Malpighian  body  is  adapted  to 
secretory  action  ;  the  expanded  glomerulus  affords  a  large 
surface  over  which  fluid  may  transude  from  the  blood  cir- 
culating in  the  capillaries  into  the  cavity  of  the  capsule  and 
uriniferous  tubule.  The  slightly  smaller  size  of  the  efferent 
vessel  is  explainable  on  the  ground  that  the  blood  entering 
by  the  afferent  vessel  loses  a  portion  of  its  fluid  through  the 
walls  of  the  glomerulus. 

The  neck  of  the  uriniferous  tubule  is  a  constricted  portion 
at  the  junction  of  the  Malpighian  body  with  the  proximal 
convoluted  tubule.  At  this  point  the  squamous  cells  of  the 
capsule  of  Bowman  become  thicker  and  merge  into  the 
cuboidal  cells  that  line  the  convoluted  tubule. 

The  proximal  convoluted  tubule,  the  first  portion  of  the 
uriniferous  tube,  is  much  twisted,  contorted,  and  bent.  It  is 
lined  with  a  single  layer  of  columnar  or  spheroidal  epithe- 
lium-cells, which  are  striated  toward  their  attached  bases ; 
these  cells  are  opaque,  granular,  somewhat  irregular  in  shape 
and  unequal  in  size,  and  of  glandular  type.  The  proximal 
convoluted  tubules  have  a  greater  calibre  than  most  portions 
of  the  uriniferous  tubules;  they  are  situated  in  the  inter- 
pyramidal  portions  of  the  cortex,  are  surrounded  by  abundant 
capillaries,  and  are  active  secretory  portions  of  the  tubules. 

The  spiral  tubule  is  the  term  applied  to  the  portion  of  the 
uriniferous  tubule  that  succeeds  the  proximal  convoluted  por- 
tion. It  is  straighter  than  the  latter,  having  only  a  slight 
spiral  twist,  and  lies  in  a  pyramid  of  Ferrein,  passing  down  to 
the  medulla.  It  is  lined  with  simple  columnar  epithelium 
resembling  that  of  the  convoluted  tubule,  but  rather  lower 
and  less  striated. 

The  descending  limb  of  Henle's  loop  begins  at  the  junction 
of  the  cortex  and  medulla,  where  the  spiral  tubule  merges 
into  it,  and  lies  in  a  Malpighian  pyramid,  passing  downward 
to  the  loop  of  Henle.  At  the  latter  point  the  uriniferous 
tubule  makes  a  sharp  U-shaped  bend  on  itself,  turning  upward 
in  an  ascending  limb. 

The  descending  limb  is  a  straight,  narrow  tube  lined  with 
a  single  layer  of  flattened  or  lenticular  epithelial  cells,  the 


BLOODVESSELS  OF  THE  KIDNEY.  165 

nuclei  of  which  cause  a  slight  bulging  at  the  centre  of  the 
cells.  As  the  nuclei  and  bulging  portions  of  the  cells  alter- 
nate on  opposite  sides  of  this  tubule  its  lumen  appears  slightly 
sinuous. 

The  ascending  limb  of  Henle's  loop  is  situated  partly  in  the 
Malpighian  pyramid  and  partly  in  the  pyramid  of  Ferrein. 
It  is  straight,  parallel  with  the  descending  limb,  and  is  lined 
with  a  single  layer  of  columnar  epithelium. 

The  irregular  tubule  is  the  portion  of  the  uriniferous  tubule 
succeeding  the  ascending  limb,  and  is  situated  in  the  inter- 
pyramidal  cortical  substance.  It  pursues  an  irregular  angular 
course,  and  is  lined  with  striated,  simple  columnar  epithelium. 

The  distal  convoluted  tubule  succeeds  the  irregular  portion, 
is  situated  in  the  interpyramidal  cortex,  and  is  similar  in  all 
respects  to  the  proximal  convoluted  portion  of  the  uriniferous 
tubule. 

The  curved  or  arched  tubule  is  a  short,  curved  tube,  in  which 
the  distal  convoluted  tubule  terminates.  It  passes  into  a 
pyramid  of  Ferrein  and  empties  into  one  of  the  straight  col- 
lecting tubules.  It  is  lined  with  low  cuboidal  epithelium 
resembling  that  of  the  straight  tubes. 

The  straight  collecting  tubes  begin  in  the  pyramids  of  Fer- 
rein and  pass  in  straight  lines  through  the  medulla  of  the 
kidney  to  the  apices  of  the  Malpighian  pyramids,  where,  hav- 
ing successively  united  into  a  smaller  number  of  ducts,  of 
larger  size,  they  empty  into  the  calices  as  above  stated. 
These  largest  discharging  ducts  are  called  the  tubes  of  Bellini. 
Into  each  collecting  tube  opens,  in  the  pyramids  of  Fer- 
rein, a  number  of  the  curved  tubules  by  which  the  secretory 
portions  of  the  uriniferous  tubules  are  connected  with  the  col- 
lecting tubes. 

In  this  manner  the  urine  secreted  by  the  secretory  tubules 
is  collected  and  discharged  into  the  pelvis  of  the  kidney. 

The  collecting  tubes  have  large  open  lumina,  and  are  lined 
with  a  single  layer  of  clear  columnar  epithelium  cells,  which 
are  shorter  in  the  cortical  portion  of  the  kidney  and  become 
longer  in  the  papillary  region  and  tubes  of  Bellini. 

The  bloodvessels  of  the  kidney  (Fig.  68)  are  branches  of 
the  renal  artery  and  vein.  These  vessels  enter  the  kidney 
at  its  hilum  and  pass  into  the  areolar  tissue  within  and  lin- 


166 


THE   URINARY  ORGANS. 


FIG.  68. 


Course  of  bloodvessels  in  the 
kidney  (Ludwig).  a,  inter- 
lobular  artery;  b,  inter- 
lobularvein;c,  Malpighian 
body,  with  afferent  and 
efferent  vessels  and  glom- 
erulus;  d.  stellate  vein; 
e,  arterise  rectrc ;  f,  venae 
rectae  ;  g,  capillaries  about 
mouths  of  outlet-ducts. 


ing  the  sinus.  They  give  off  twigs 
which  supply  this  region  and  divide 
into  a  number  of  branches,  the  arterice 
and  venae  proprice  renales,  which  pass 
outward  in  the  columnse  Bertini,  be- 
tween the  Malpighian  pyramids. 

On  reaching  the  bases  of  these  pyra- 
mids they  divide  into  the  arcuate  ar- 
teries and  veins,  which  follow  the 
boundary  between  the  cortical  and 
medullary  regions  and,  anastomosing 
with  one  another,  form  complete  ar- 
terial and  venous  arches  over  the  bases 
of  the  Malpighian  pyramids.  From 
these  arches  two  sets  of  small  vessels 
are  given  off,  one  the  interlobular,  pass- 
ing radially  outward  into  the  cortex  ; 
the  other,  the  vasa  recta,  converging 
inward  to  supply  the  medulla. 

The  interlobular  arteries,1  or  cortical 
arteries,  are  small  straight  branches 
from  the  arterial  arches  passing  radially 
outward  in  the  interpyramidal  cortical 
regions,  midway  between  the  pyramids 
of  Ferrein.  They  give  off  a  small 
twig  to  each  of  the  Malpighian  bodies 
along  their  course,  which  enters  the 
glomerulus  as  its  afferent  vessel.  In 
the  glomerulus  the  afferent  vessel 
breaks  up  into  a  capillary  tuft;  the 
capillaries  then  reunite  to  form  a  single 
efferent  vessel  leaving  the  glomerulus. 
These  efferent  vessels  then  mostly 

1  Each  pyramid  of  Ferrein,  with  the  tributary 
interpyramidal  tubules  in  its  vicinity,  may  be 
regarded  as  a  distinct  section  or  physiological 
lobule  of  the  renal  cortex,  though  they  are  not 
marked  off' from  one  another  by  definite  bound- 
aries into  distinct  lobules.  The  cortical  arteries 
pass  between  these  sections  or  lobules,  whence 
the  term  interlobular. 


SECRETION  OF  THE   URINE.  167 

break  up  into  another  capillary  network  enveloping  the  uri- 
niferous  tubules  in  the  pyramids  and  interpyramidal  regions 
of  the  cortex.  These  capillaries  then  unite  again  and  empty 
into  the  interlobular  veins,  which  occupy  a  situation  corre- 
sponding to  that  of  the  interlobular  arteries,  and  empty  into 
the  venous  arches.  The  capillaries  beneath  the  capsule  unite 
in  venous  branches,  the  stellate  veins,  which  meet  in  a  star- 
shaped  manner  and  empty  into  the  interlobular  veins. 

The  arteriae  rectas  are  small  straight  arterioles  which  arise 
in  large  numbers  from  the  concave  sides  of  the  arterial  arches 
and  pass  into  the  Malpighian  pyramids,  converging  to  the 
apices  of  the  latter.  They  divide  into  elongated  capillary 
meshes  embracing  the  uriniferous  tubules  of  the  medulla. 
A  few  arteriolae  recta?  are  also  derived  from  afferent  vessels 
of  some  of  the  glomeruli,  which  pass  into  the  medulla,  instead 
of  breaking  up  into  capillaries  in  the  cortex.  The  blood  from 
the  medullary  capillaries  is  collected  by  the  vence  rectce,  which 
are  arranged  similarly  to  the  arteriae  recta?  and  empty  into 
the  venous  arches. 

The  structures  composing  the  different  parts  of  the  kidney 
may  be  recapitulated  as  follows  :  the  interpyramidal  portions 
of  the  cortex  contain  the  Malpighian  bodies,  the  proximal 
and  distal  convoluted  tubules,  the  irregular  tubules,  the  curved 
tubules,  and  the  interlobular  vessels. 

The  pyramids  of  Ferrein  contain  the  spiral  tubules,  part  of 
the  ascending  limbs  of  Henle's  loops,  and  portions  of  the 
straight  collecting  tubes. 

The  medulla  contains  the  descending  and  part  of  the 
ascending  limbs  of  Henle's  loops,  part  of  the  straight  collect- 
ing tubes,  the  tubes  of  Bellini,  and  the  vasa  recta. 

The  secretion  of  the  urine  is  accomplished  somewhat  as  fol- 
lows :  In  the  Malpighian  bodies  fluid  transudes  or  filters  from 
the  blood  through  the  thin  capillary- walls  and  squamous  cells 
into  the  cavity  of  the  capsule  of  Bowman.  The  fluid  thus 
separated  is  supposed  to  be  mainly  water,  with  very  little 
solids.  The  glandular  epithelium  of  other  portions  of  the 
tubules,  the  convoluted  tubules  especially,  then  remove  from 
the  blood  in  the  surrounding  capillaries  the  solid  constituents 
of  the  urine  by  a  true  secretory  process  ;  these  solids  are  dis- 
solved by  the  fluid  passing  down  the  tubules. 


168  THE   URINARY  ORGANS. 

The  pelvis  of  the  kidney,  centrally  situated  at  one  side,  is 
continuous  with  or  forms  the  upper  extremity  of  the  ureter. 

This  expanded  upper  end  of  the  ureter  divides  into  two  or 
three  divisions  or  infundibula,  and  these  into  calices  into 
which  the  apices  of  the  Malpighian  pyramids  project  as 
papillce. 

The  wall  of  the  renal  pelvis  consists  of  three  layers,  mucous 
(composed  of  epithelium  and  a  tunica  propria),  muscular,  and 
fibrous  or  areolar.  The  superficial  layer  of  the  mucosa  con- 
sists of  stratified  squamous  epithelium,  of  the  variety  called 
transitional,  made  up  of  a  few  layers  of  cells  rapidly  changing 
from  the  deeper  spheroidal  to  the  superficial  squamous  form. 
The  epithelium  rests  on  a  fibrous  tunica  propria,  beneath  which 
is  a  fibro-muscular  layer,  containing  involuntary  muscle-cells. 
Underneath  the  latter  is  a  broad  layer  of  fibrous  tissue. 
Within  the  renal  sinus  is  a  variable  amount  of  areolar  tissue, 
extending  to  the  kidney-parenchyma,  and  usually  containing 
considerable  masses  of  adipose  tissue.  In  this  areolar  tissue 
the  larger  arteries  and  veins  of  the  kidney  are  situated  and 
subdivide.  The  mucosa  is  said  to  contain  a  few  small  race- 
mose glands,  though  the  presence  of  such  glands  in  the  urinary 
tract  is  disputed. 

The  ureter  is  continuous  with  the  renal  pelvis,  and  its  walls 
consist  of  three  coats,  mucous,  muscular,  and  fibrous. 

The  mucous  coat,  which  in  the  contracted  ureter  is  thrown 
into  longitudinal  folds,  consists  of  a  lining  of  transitional 
epithelium,  resting  on  a  fibrous  layer  which  represents  a 
tunica  propria  and  submucous  layer.  The  mucosa  is  said  to 
contain  a  few  small  racemose  mucous  glands. 

Outside  the  mucosa  is  the  muscular  coat,  composed  of  in- 
voluntary muscle  in  three  layers,  an  inner  longitudinal,  a  mid- 
dle circular,  and  in  the  lower  portion  of  the  ureter  a  thin 
outer  longitudinal  layer.  Surrounding  the  muscular  coat  is 
an  areolar  or  fibrous  layer. 

The  Bladder. 

The  walls  of  the  bladder  consist  of  three  coats — mucous, 
muscular,  and  fibrous,  from  within  outward. 

The  mucous  coat,  which  is  thrown  into  folds  when  the  organ 


THE   URETHRA.  169 

is  contracted,  consists  of  an  epithelial  layer,  tunica  propria,  and 
submucosa. 

The  epithelium  lining  the  bladder  consists  of  a  few  layers  of 
stratified  squamous  or  transitional  epithelium  (Fig.  12),  con- 
tinuous with  and  similar  to  that  lining  the  ureters  and  renal 
pelvis.  The  superficial  layer  of  cells  in  the  epithelium  is  a 
stratum  of  thick,  squamous,  or  lenticular  cells,  possessing 
sometimes  more  than  one  nucleus  each  ;  the  lower  surfaces  of 
these  cells  exhibit  indentations  into  which  the  underlying  cells 
project.  The  cells  beneath  this  outermost  layer  are  oval  or 
pyriform  and  perpendicular  to  the  surface ;  the  two  or  three 
layers  beneath  these  are  spheroidal  or  irregular  germinal  epi- 
thelial cells. 

The  epithelium  rests  on  a  firm  fibrous  tunica  propria ;  be- 
neath this  is  a  layer  of  loose  or  areolar  submucous  tissue  con- 
tinuous with  the  fibrous  tissue  permeating  the  muscular  coat. 
A  few  small  racemose  mucous  glands  are  said  to  be  present  in 
the  mucosa  of  the  base  of  the  bladder. 

Outside  the  submucosa  is  the  thick  muscular  layer,  composed 
of  fasciculi  of  involuntary  muscle  supported  in  fibrous  tissue. 
The  arrangement  of  the  muscular  fasciculi  is  rather  indefinite, 
but  in  general  three  layers  can  perhaps  be  distinguished :  an 
inner  longitudinal  layer ;  a  middle  circular  layer,  thickened 
at  the  neck  of  the  bladder  to  form  the  sphincter  vesicse ;  and 
an  outer  longitudinal  layer. 

Outside  of  the  muscular  coat  is  a  fibrous  layer,  of  areolar 
tissue,  which  over  a  large  portion  of  the  fundus  of  the  bladder 
is  covered  by  peritoneum. 

The  Urethra. 

The  female  urethra  is  lined  internally  with  epithelium,  strati- 
fied squamous,  or  sometimes,  it  is  said,  simple  columnar.  The 
epithelium  rests  on  a  firm  tunica  propria,  which,  especially 
toward  the  meatus,  has  papillae  projecting  into  the  epithelium. 
Beneath  the  tunica  propria  is  a  loose  submucosa,  which  con- 
tains expanded  venous  sinuses  forming  an  erectile  tissue. 
Small  racemose  mucous  glands  (urethral  or  Littre's  glands) 
also  occur  in  the  submucosa,  most  numerous  at  the  meatus. 
The  mucosa,  consisting  of  the  above-mentioned  layers,  lies  in 


170  THE   URINARY  ORGANS. 

longitudinal  folds.  Outside  the  submucous  tissue  is  a  well- 
marked  non-striated  muscular  coat,  having  an  inner  longitudi- 
nal and  outer  circular  layer,  and  intermingled  with  elastic 
tissue.  Outside  the  muscular  coat  is  fibrous  tissue,  in  which 
the  urethra  is  imbedded. 

The  male  urethra :  The  walls  of  the  male  urethra  are  com- 
posed of  epithelium  resting  on  a  tunica  propria  (forming  a 
mucous  coat),  submucous  tissue,  and  muscular  tissue,  and  con- 
tain numerous  mucous  glands. 

The  epithelium  lining  the  male  urethra  is  of  the  transitional 
variety  at  the  vesical  end,  then  changes  to  stratified  columnar ; 
throughout  the  middle  and  longest  portion  (penile)  it  is  sim- 
ple columnar,  and  for  a  short  distance  back  of  the  meatus  is 
of  the  stratified  squamous  type. 

The  epithelial  layer  rests  on  a  fibrous  tunica  propria  which 
toward  the  meatus  sends  papillae  into  the  epithelium. 

These  layers  form  the  mucosa,  which  in  the  flaccid  condition 
of  the  canal  lies  in  longitudinal  folds. 

Outside  the  tunica  propria  is  the  submucous  layer  of  areolar 
and  loose  fibrous  tissue. 

In  the  penile  portion  of  the  urethra  the  submucous  tissue 
merges  into  the  cavernous  or  erectile  tissue  of  the  corpus 
spongiosum,  which  is  enveloped  in  a  strong  fibrous  sheath. 

The  submucosa  along  the  entire  course  of  the  male  urethra 
contains  small  racemose  mucous  glands,  the  urethral  glands  or 
glands  of  Littre,  lined  with  columnar  epithelium  and  opening 
into  the  urethral  canal  ;  in  the  penile  portion  these  glands  are 
scattered  throughout  the  erectile  tissue. 

The  muscular  coat  of  the  urethra  lies  outside  or  within  the 
submucous  coat.  In  the  prostatic  and  membranous  portions 
the  muscular  layer  lies  beneath  the  submucosa,  and  consists  of 
inner  longitudinal  and  outer  circular  fasciculi  of  non-striated 
muscle. 

Outside  these  muscular  layers  in  the  membranous  urethra 
is  an  additional  muscle,  the  voluntary  compressor  urethrse. 

In  the  penile  portion  of  the  urethra  the  muscular  layer  is 
imbedded  in  the  submucous  tissue.  Near  the  bulb  the  inner 
longitudinal  and  outer  circular  layers  of  smooth  muscle  are 
still  present ;  but  anteriorly  the  circular  layer  disappears  and 
the  longitudinal  fasciculi  become  thinned  and  scattered. 


URJNE.  171 

The  urethra  is  surrounded  in  its  prostatic  portion  by  the 
prostate ;  in  its  penile  portion  by  the  corpus  spongiosum  ;  be- 
tween these  two  portions  is  a  short  interval,  the  membranous 
portion,  in  which  the  urethra  is  supported  in  fibrous  tissue. 

The  urine  is  a  clear,  homogeneous,  serous  secretion,  contain- 
ing a  slight  amount  of  mucus.  A  very  few  adventitious  ele- 
ments may  be  normally  present — detached  epithelium-cells, 
mucous  corpuscles,  stray  leukocytes,  and  spermatozoa.  In 
abnormal  conditions  a  variety  of  organic  formed  elements  and 
crystalline  or  amorphous  solid  substances  may  appear. 


CHAPTER   XIV. 

THE   REPRODUCTIVE  SYSTEM. 

THE  consideration  of  the  organs  of  reproduction  naturally 
falls  into  two  parts,  those  of  the  male  and  those  of  the  female. 

MALE  GENITAL  ORGANS. 

The  male  genital  organs  consist  of  the  testicles,  the  epidid- 
ymis,  the  vas  deferens,  the  seminal  vesicles,  the  prostate, 
Cowper's  glands,  and  the  penis,  besides  vestiges  of  foatal 
structures.  The  main  portion  of  these,  the  testes  and  seminal 
ducts,  are  derived  from  the  embryonic  Wolffian  body,  and 
their  epithelium  is  therefore  of  mesoblastic  origin. 

The  scrotum,  the  pouch  containing  the  testicles,  is  covered 
externally  with  skin,  thin  and  plicated.  Beneath,  and  closely 
connected  with  the  skin,  is  the  dartos,  a  layer  of  vascular 
contractile  tissue  composed  of  areolar  tissue  and  involuntary 
muscle.  A  septum  from  the  dartos  divides  the  scrotum  into 
lateral  halves.  Beneath  the  dartos  are  strata  of  areolar  and 
fibrous  tissue — the  intercolumnar  fascia,  cremasteric  fascia,  and 
fascia  propria ;  the  cremasteric  fascia  also  contains  strands  of 
striated  and  non-striated  muscle.  Beneath  these  layers  is  the 
parietal  layer  of  the  tunica  vaginalis,  a  closed  serous  sac 
derived  from  the  peritoneum  and  invaginated  into  itself  to 
form  a  covering  for  the  testicle. 

The  Testicle. 

The  testicle  is  a  compound  tubular  gland  in  which  the 
spermatozoa  are  generated.     Attached  to  the  posterior  aspect 
of  the  testicle  is  the  epididymis,  which  consists  of  a  body,  an 
expanded  upper  extremity,  or  head,  called  the  globus  major, 
and  a  smaller  lower  extremity,  or  tail,  the  globus  minor. 
The  testicle  is  essentially  a  congeries  of  tubules,  secretory 
172 


SEMINIFEROUS  TUBULES.  173 

and  conducting,  called  the  seminiferous  tubules,  supported  in 
a  connective-tissue  framework.  It  is  well  supplied  with 
bloodvessels,  and  also  has  lymph-channels;  its  nerve-supply  is 
inconspicuous  and  obscure. 

The  surface  of  the  testis  is  covered  with  a  serous  membrane, 
the  visceral  layer  of  the  tunica  vaginalis  ;  this  sac  is  invagi- 
nated  over  the  testis  from  behind,  leaving  a  hiatus  or  hilum 
for  the  entrance  of  the  elements  of  the  spermatic  cord. 

The  sustentacular  connective  tissue  of  the  testis  consists  of 
the  tunica  albuginea,  mediastinum  testis,  and  interlobular  and 
intertubular  tissue. 

The  tunica  albuginea  is  a  dense  fibrous  capsule  enveloping 
the  organ,  lying  underneath  and  merging  into  the  visceral 
layer  of  the  tunica  vaginalis.  At  the  posterior  part  of  the 
testis  the  tunica  albuginea  is  thickened,  forming  a  longitudinal 
ridge  or  mass  called  the  mediastinum  testis,  or  corpus  of  High- 
more;  this  contains  a  system  of  communicating  spaces,  the 
rete  testis. 

In  infancy  numerous  well-marked  fibrous  partitions  (inter- 
lobular septa)  radiate  from  the  mediastinum  testis  and,  extend- 
ing across  toward  the  tunica  albuginea  opposite,  divide  the 
testicle  into  a  number  of  conical  compartments  or  lobules, 
with  their  apices  directed  toward  the  mediastinum. 

The  adult  and  fully  developed  testicle,  however,  is  often 
less  completely  and  less  conspicuously  divided  into  lobules, 
the  interlobular  septa  being  occasional  rather  indefinite  fibrous 
laminae,  a  little  thicker  than  the  intertubular  septa. 

Lining  the  interlobular  septa  and  the  inner  surface  of  the 
tunica  albuginea  is  the  tunica  vasculosa,  a  layer  of  areolar 
tissue  containing  abundant  bloodvessels. 

The  individual  seminiferous  tubules  are  separated  from  one 
another  by  the  intertubular  tissue,  thin  connective  tissue  parti- 
tions containing  capillaries  and  providing  basement-membranes 
for  the  tubules.  In  places  within  the  intertubular  tissue  are 
situated  groups  of  large  spheroidal  epithelioid  (?)  cells,  inter- 
stitial cells. 

The  seminiferous  tubules  exhibit  several  divisions,  which  are, 
from  their  beginning  onward,  as  follows  :  convoluted  tubules, 
tubuli  recti,  rete  testis,  vasa  efferentia,  and  epididymis.  The 
convoluted  portions  generate  the  spermatozoa,  the  remaining 


174  THE  REPRODUCTIVE  SYSTEM. 

seminal  ducts  are  conducting-channels  or  secrete  fluid  constit- 
uents of  the  semen. 

The  convoluted  tubules  are  single  or  branched  tubes,  of 
large  diameter,  coiled,  bent,  and  twisted  in  intricate  convolu- 
tions, closely  packed  together  so  as  to  fill  practically  the  entire 
testicles.  They  are  surrounded  by  well-marked  basement- 
membranes,  and  their  coils  are  separated  from  one  another  by 
the  thin  intertubular  connective  tissue.  The  tubules  are  lined 
by  several  layers  of  epithelium,  from  which  the  spermatozoa 
are  generated. 

The  deepest  or  parietal  layer  of  epithelium  consists  of  large 
spheroidal  spermatogenic  cells  ("  spermatogonia  ")  resting  on 
the  basement-membrane,  among  which  are  occasional  long 
sustentacular  cells  (" cells "  or  "columns  of  Sertoli")  projecting 
inward  among  the  other  cells  toward  the  lumen. 

Upon  these  parietal  cells  rests  a  layer  or  two  of  large 
spheroidal  cells,  mother-cells,  derived  from  the  "  spermato- 
gonia." Next  internal  to  these  are  a  greater  number  of 
smaller  spherical-cells  ;  these  are  called  daughter-cells  (also 
called  "  spermatids  "  and  "  spermatoblasts  "),  and  are  derived 
from  the  mother-cells. 

The  daughter-cells  elongate  and  develop  into  the  sperma- 
tozoa, (described  below),  which  are  located  in  clusters,  their 
heads  (until  they  become  separated)  being  attached  to  the 
daughter-cells  and  their  tails  projecting  into  the  lumen.  The 
lumen  of  the  tubules  contains,  besides  the  spermatozoa,  a 
broken-down  granular  material. 

Spermatogenesis :  The  development  of  the  successive  layers 
and  generations  of  spermatogenic  cells  and  the  spermatozoa 
takes  place  by  karyokinesis. 

All  parts  of  the  seminiferous  tract  are  not  simultaneously 
engaged  in  active  cell-division,  but  the  different  stages  of  the 
process  are  observable  in  different  regions  at  the  same  time. 
While  karyokinesis  and  the  production  of  spermatozoa  are 
actively  going  on  in  some  places,  in  others  the  cells  are 
quiescent  and  spermatozoa  absent.  Some  of  the  details  of 
the  process  of  generation  of  the  spermatozoa  are  still  undeter- 
mined or  in  dispute.  It  is  supposed  that  during  their 
generation  the  number  of  chromosomes  of  the  spermatozoa 


TUUULE  RECTI  OR  STRAIGHT  TUBULES.          175 

becomes  "  reduced  "  to  half  the  number  characteristic  of  the 
cells  of  the  species  (page  36),  so  that  when  joined  to  the 
female  element,  likewise  reduced  (page  39),  the  fertilized 
ovum  possesses  the  normal  number  of  chromosomes  (sixteen 
in  man). 

As  the  spermatozoa  are  endowed  with  the  power  of  transmitting  to 
the  offspring  the  characteristics  of  the  parent,  the  process  of  spermato- 
genesis  is  a  link  in  the  chain  of  heredity.  The  mode  by  which  the 
parent  implants  or  involves  his  own  characteristics  within  the  minute 
compass  of  a  spermatozoon,  so  that  the  latter  in  its  further  develop- 
ment reproduces  its  kind,  is  a  biological  question  of  great  importance. 

The  characters  of  the  parent  are  either  congenital  (racial,  inherited) 
or  acquired;  the  latter  few  in  number,  the  former  multitudinous. 
Many  biologists  contend  that  characteristics  acquired  by  an  individual 
subsequent  to  his  conception  and  birth  cannot  be  transmitted  to  his 
offspring;  but  supposing  it  possible,  what  mechanism  exists  in  the 
genital  organs  by  which  the  features  of  a  distant  part  of  the  body  can 
be  impressed  upon  spermatozoa  developing  in  the  testicle  so  as  to  be 
carried  on  to  the  progeny  ?  Obviously  the  only  channels  by  which 
impressions  or  influences  from  other  parts  could  be  conveyed  to  the 
testicle  are  the  circulation  and  the  nerves.  The  testes  are  amply  sup- 
plied with  bloodvessels;  not  so  well,  perhaps,  with  nerves.  We  can 
conceive  how,  in  conditions  of  toxaemia  or  generally  lowered  vitality, 
an  impoverished  or  toxic  blood  could  alter  or  lower  the  vitality  of  the 
spermatogenic  cells  and  thus  convey  a  deteriorating  tendency  to  the 
offspring;  and  we  are  also  familiar  with  trophic  nervous  effects;  but 
aside  from  these,  the  manner  in  which  bodily  features  might  become 
impressed  on  the  spermatogenic  cells  through  nervous  or  circulatory 
influences  is  obscure. 

Little  is  known  likewise  as  to  just  how  the  congenital  or  inherited 
features  of  the  parent,  the  fixed  and  stable  characters  of  the  race,  are 
carried  over  from  generation  to  generation.  Amidst  the  vast  multi- 
tude and  diversity  of  cells  making  up  the  body,  what  line  of  cellular 
transmission  of  racial  features  connects  the  'ovum,  from  which  an 
organism  develops,  with  the  ovules  or  spermatozoa  of  the  next  genera- 
tion which  after  a  time  appear  in  the  body  of  the  parent  ? 

Many  biologists  regard  the  cells  into  which  an  ovum  develops  as  of 
two  fundamentally  different  kinds :  somatic  cells,  making  up  the  body 
generally ;  and  germ-cells,  to  which  the  developmental  powers  of  the 
ovum  are  transmitted.  According  to  this  theory,  the  spermatogenic 
cells  of  the  testicle  and  the  corresponding  cells  of  the  ovary  are  direct 
descendants  of  the  ovum  through  a  succession  of  germ-cells  (located 
in  the  sexual  glands),  which  have  carried  on,  in  isolated  continuity  as 
it  were,  the  reproductive  potentialities  inherent  in  the  ovum. 

The  tubuli  recti  or  straight  tubules:  The  convoluted  tubules 
converge  toward  the  mediastinum  testis,  and  at  their  proximal 


176  THE  REPRODUCTIVE  SYSTEM. 

ends  terminate  in  short  straight  tubules  which  empty  into  the 
channels  forming  the  rete  testis.  These  tubuli  recti  are  nar- 
rower in  calibre  than  the  convoluted  portions,  and  are  lined 
with  a  single  layer  of  low  columnar  or  cuboidal  epithelium- 
cells. 

The  rete  testis  is  a  network  of  anastomosing  channels  and 
sinuses  formed  by  the  union  of  the  tubuli  recti.  These  chan- 
nels are  situated  in  the  substance  of  the  mediastinum  testis, 
and  are  lined  with  a  single  layer  of  flattened  epithelial  cells 
resting  on  the  surrounding  fibrous  tissue. 

The  vasa  efferentia :  The  seminiferous  channels  of  the  rete 
testis  at  its  upper  end  continue  upward  in  the  form  of  ten  to 
fifteen  efferent  vessels,  the  outlet-ducts  of  the  testis,  which 
pass  through  the  tunica  albuginea  and  enter  the  globus  major, 
where  they  form  the  coni  vasculosi.  These  vasa  efferentia  are 
lined  with  stratified  columnar  epithelium,  partly  ciliated  •  the 
epithelium  cells  are  thrown  up  into  ridges  and  papilla?  which 
project  into  the  interior  of  the  tubules  and  give  the  free 
surface  a  sinuous  and  undulating  character.  The  epithelium 
rests  on  a  basement-membrane  and  thick  fibrous  A 
taining  involuntary  muscle-cells  arranged  transversely. 

In  the  globus  major  the  efferent  tubules  are  coiled  and  con- 
volu£ed,  making  up  the  coni  vasculosi  (or  lobuli  epididymidis\ 
each  tube  forming  a  conical  mass  or  lobule.  The  globus  major 
is  made  up  of  these  lobules. 

The  several  tubes  forming  the  coni  vasculosi  unite  ulti- 
mately into  one  tube  which  continues  downward  and  onward 
as  the  canal  of  the  epididymis. 

The  epididymis  consists  macroscopically  of  a  body,  a  head 
or  globus  major  above,  and  a  globus  minor  below7.  The  globus 
major  is  intimately  connected  with  the  testis  by  the  vasa 
efferentia  ;  the  globus  minor  is  attached  to  the  testis  by  fibrous 
tissue ;  the  body  of  the  epididymis  mainly  by  the  tunica 
vaginalis. 

The  body  and  globus  minor  of  the  epididymis  are  made 
up  of  the  windings  of  the  canal  of  the  epididymis,  which  is 
the  continuation  of  the  united  vasa  efferentia.  The  canal  of 
the  epididymis  is  a  single  long  continuous  tube,  coiled,  con- 
voluted, and  packed  into  small  compass  ;  it  is  lined  with  strat- 
ified ciliated  epithelium,  resting  on  a  basement-membrane  and 


SEMINAL    VESICLE.  177 

surrounded  by  fibrous  tissue  containing  transverse  involuntary 
muscle-cells.  The  coils  of  the  canal  are  imbedded  in  and 
separated  by  areolar  tissue,  and  the  whole  epididymis  is 
enveloped  in  a  fibrous  capsule.  At  the  lower  end  of  the 
epididymis  its  canal  becomes  and  continues  onward  as  the 
vas  deferens. 

Various  remnants  of  foetal  structures  (vestiges  of  the  AVolf- 
fian  body)  are  found  about  the  testicle. 

The  paradidymiSj  or  organ  of  Giraldes,  is  situated  in  the 
connective  tissue  of  the  epididymis,  and  consists  of  a  few 
closed  convoluted  tubules  lined  with  epithelium.  The  vas 
aberrans  is  a  tube  similar  to  the  vas  deferens,  and  is  some- 
times found  branching^  off  from  the  lower  part  of  the  latter, 
or  canal  of  the  epididymis,  passes  up  the  spermatic  cord  for 
a  variable  short  distance,  and  has  a  blind  upper  end.  The 
hydatids  of  Morgagni  are  small  pedunculatecl  bodies,  contain- 
ing areolar,  epithelial,  or  vascular  tissue,  attached  to  the  upper 
part  of  the  testis  or  epididymis. 

The  vas  deferens,  the  continuation  of  the  lower  end  of  the 
canal  of  the  epididymis,  forms  one  of  the  constituents  of  the 
spermatic  cord,  and  extends  to  the  base  of  the  bladder,  where 
it  becomes  dilated  (forming  the  "ampulla")  and  unites  with 
the  outlet  of  the  seminal  vesicle.  It  is  a  firm  cordy  tube, 
and  its  walls  consist,  from  within  outward,  of  a  mucous,  sub- 
mucous,  muscular,  and  fibrous  coat. 

The  mucous  coat  is  lined  with  stratified  columnar  epithe- 
lium, ciliated  for  a  short  distance  at  the  beginning  of  the  vas, 
but  non-ciliated  in  the  remaining  greater  portion  of  the  canal ; 
the  epithelium  rests  on  a  tunica  propria,  which  is  surrounded 
by  submucous  areolar  tissue.  The  mucosa  is  thrown  into 
longitudinal  folds  in  the  va§,  and  in  the  ampulla  into  irregular 
ruga?  and  plications.  Small  glands  occur  in  the  mucosa  in 
the  ampulla. 

The  muscular  coat  is  composed  of  an  inner  circular  and  outer 
longitudinal  layer  of  involuntary  muscle,  intermingled  with 
fibrous  tissue.  Outside  the  muscle  is  a  layer  of  fibrous  and 
areolar  tissue. 

The  seminal  vesicle  is  a  sacculated  pouch,  largely  of  glandu- 
lar character,  branching  off  from  the  vas  deferens.  Its  outlet 

12— Hist. 


178  THE  REPRODUCTIVE  SYSTEM. 

unites  with  the  vas  deferens  to  form  the  ejaculatory  duct.  Its 
walls  are  similar  in  structure  to  those  of  the  vas.  It  is  lined 
with  columnar  epithelium,  which  rests  on  a  tunica  propria, 
beneath  which  is  submucous  areolar  tissue.  Its  mucosa  is 
thrown  into  interlacing  rugae  and  plications,  which  form  sac- 
cular  and  somewhat  gland-like  recesses ;  the  mucous  coat  also 
contains  small  glands.  Beneath  the  submucosa  is  an  inner 
circular  and  outer  longitudinal  layer  of  involuntary  muscle, 
outside  of  which  is  areolar  tissue. 

The  ejaculatory  ducts,  one  on  each  side,  are  formed  by  the 
union  of  the  vasa  deferentia  with  the  outlets  of  the  seminal 
vesicles.  They  are  situated  partly  within  the  prostate,  and 
empty  into  the  prostatic  urethra.  They  are  lined  with  simple 
columnar  epithelium,  resting  on  connective  tissue ;  outside  the 
latter  are  thin  inner  circular  and  outer  longitudinal  layers  of 
involuntary  muscle. 

The  prostate  gland  is  a  compound  tubular  gland,  the  mu- 
cous secretion  of  which  enters  into  the  composition  of  the 
semen.  It  surrounds  a  portion  of  the  urethra  and  ejaculatory 
ducts.  It  is  made  up  of  sustentacular  connective  tissue,  invol- 
untary muscle,  and  secreting  alveoli,  besides  vessels  and  nerves. 

The  sustentacular  connective  tissue  consists  of  a  firm  fibrous 
capsule,  septa  traversing  the  organ  in  various  directions,  and 
interalveolar  tissue.  Intermingled  with  and  accompanying 
the  connective  tissue  throughout  the  organ,  forming  in  many 
places  the  greatest  part  of  its  framework,  is  a  large  amount 
of  involuntary  muscle,  in  the  capsule  and  septa,  between  the 
alveoli,  and  surrounding  the  urethra. 

The  glandular  alveoli  of  the  prostate  are  of  a  racemose  or 
compound  tubular  character,  and  are  lined  with  columnar 
epithelium. 

Their  ducts  unite  to  form  twelve  to  twenty  outlet-ducts 
opening  into  the  urethra — •/.  f.,  the  " prostatic  sinus"  on  each 
side ;  the  epithelium  lining  the  ducts  merges  into  the  squa- 
mous  type  of  the  urethra.  Many  of  the  alveoli  contain  minute 
round,  concentrically  marked  calculous  granules,  or  prostatic 
concretions.  From  the  lower  surface  of  the  urethra  a  short 
small  cul-de  sac  extends  into  the  prostate ;  this  is  called  the 
sinus  pocularis  or  uterm  masculinus,  and  is  homologous  to  the 
female  uterus. 


CORPORA   CAVERNOSA. 


179 


Cowper'  s  glands,  situated  beneath  the  membranous  urethra 
between  the  layers  of  the  deep  perineal  fascia,  are  two  small 
racemose  glands  emptying  into  the  urethra.  The  alveoli  are 
lined  with  columnar  epithelium  apparently  of  the  mucous 
type,  though  the  purpose  of  the  secretion  is  not  well  under- 
stood. 

The  Penis. 

The  penis  consists  of  three  longitudinal  cylindrical  com- 
partments surrounded  by  fibrous  sheaths — two  corpora  caver- 
nosa  filled  with  erectile  tissue,  and  the  corpus  spongiosum  con- 
taining erectile  tissue  and  the  urethra — all  covered  with  skin 

FIG.  69. 


Cavernous  or  erectile  tissue  of  penis  (Cadiat).    a,  fibrous  trabeculae ;  b,  cavernous 
sinuses ;  c,  smooth  muscle  in  cross-section. 

and  subcutaneous  tissue.  The  skin  is  thin  and  movable.  The 
subcutaneous  areolar  tissue  is  free  from  fat,  contains  vascular 
and  nerve  trunks,  and  by  its  looseness  allows  the  skin  much 
play. 

The  corpora  cavernosa  are  surrounded  by  a  common  sheath 
of  dense  fibrous  tissue,  the  tunica  albuguinea.     Each  corpus 


180  THE  REPRODUCTIVE  SYSTEM. 

cavernosum  is  also  enveloped  by  a  dense  fibrous  sheath  of 
its  own,  lying  just  within  the  common  sheath  J  the  septum 
(u  pectiniform  ")  thus  formed  between  the  two  corpora  is,  how- 
ever, incomplete  and  interrupted.  From  these  sheaths  fibrous 
trabeculse  are  given  off  which  traverse  the  interior  of  the 
corpora  in  all  directions,  branching  and  anastomosing  so  as 
to  divide  them  into  a  spongy  system  of  spaces  or  sinuses  com- 
municating freely  with  one  another.  The  fibrous  trabeculce  con- 
tain some  involuntary  muscle  and  elastic  tissue,  and  convey 
vessels  and  nerves.  The  sinuses  formed  by  the  septa  are  lined 
with  endothelium,  and  into  them  open  the  bloodvessels,  so 
that  they  form  a  system  of  cavernous  spaces  or  vascular 
sinuses,  through  which  the  blood  flows,  from  the  arteries  and 
into  the  veins  (Fig.  69).  This  arrangement  constitutes  erectile 
tissue.  When  the  venous  outflow  is  cut  off  by  muscular  action 
blood  accumulates  in  the  sinuses,  causing  the  penis  to  become 
turgid  and  erect. 

The  corpus  spongiosum  is  a  compartment  filled  with  erectile 
tissue  and  containing  the  urethra.  Its  posterior  end,  slightly 
expanded,  forms  the  bulb  ;  its  anterior  end,  the  glans  penis.  It 
is  enveloped  in  a  firm  fibro-elastic  sheath  containing  a  small 
amount  of  involuntary  muscle.  From  the  sheath  fibro-elastic 
trabeculge,  containing  occasional  non-striated  muscle,  traverse 
the  corpus  and  divide  it  into  vascular  sinuses,  forming  erectile 
tissue  like  that  of  the  corpora  cavernosa.  Along  the  axis  of 
the  corpus  spongiosum  passes  the  urethra  (more  fully  de- 
scribed above)  surrounded  by  the  erectile  tissue,  which  merges 
into  the  submucous  tissue  of  the  urethra.  The  urethra  is 
lined  with  columnar  epithelium  and  into  it  open  numerous 
mucous  urethral  glands  (the  "  glands  of  Littre),  which  are 
scattered  about  in  the  erectile  tissue  of  the  corpus  spongiosum. 

The  glans  penis  is  an  expansion  of  the  anterior  extremity 
of  the  corpus  spongiosum,  covered  by  closely  adherent  mucous 
membrane.  The  mucous  membrane,  continuous  with  that 
of  the  urethra,  is  lined  with  stratified  squamous  epithelium, 
resting  upon  a  tunica  propria,  the  surface  of  which  is  studded 
with  papilla3  containing  numerous  special  sensory  nerve-ter- 
minals. At  the  corona  and  base  of  the  glans  the  mucous 
membrane  contains  abundant  sebaceous  glands,  the  glandulm 
odoriferce  or  glands  of  Tyson,  unassociated  with  hairs,  the 


SPERMATOZOA. 


181 


— c 


odorous  secretion  of  which  enters  into  the  formation  of  the 
smegma.  The  raucous  covering  of  the  glans  is  reflected  over 
the  inner  surface  of  the  prepuce  and  at  its  margin  merges 
into  the  skin. 

The  semen,  as  finally  ejaculated,  consists  of  an  immense 
number  of  special  cellular  elements  (spermatozoa)  suspended 
in  fluid  (liquor  seminis),  together  with  granular,  crystalline, 
and  adventitious  matter.  The  liquor  seminis  is  derived  from 
various  parts  of  the  seminal  tract, 
especially  the  seminal  vesicles,  pros-  FIG.  70. 

tate,  and  Cowper's  glands.  It  is  a 
muco-al numinous  fluid  containing 
various  chemical  ingredients.  It 
exhibits  fine  granular  matter  (cel- 
lular and  protoplasmic  debris),  and, 
in  small  number,  cast-off  epithelium- 
cells,  stray  leukocytes,  clear  "  hyaline 
bodies"  from  the  seminal  vesicles, 
fat  and  lecithin  particles,  and  the 
small  prostatic  concretions  or  "  amy- 
loid bodies."  After  standing,  crys- 
tals are  deposited  in  the  semen,  es- 
pecially characteristic  slender  octa- 
hedral crystals  of  spermin  phosphate. 

The  spermatozoa  of  different  species 
of  animals  exhibit  characteristic  dif- 
ferences though  the  general  structure 
remains  similar ;  the  same  is  the  case 
with  the  homologous  pollen  of  plants. 

The  spermatozoon  of  man  (Fig.  70) 
is  made  up  of  a  head  3  to  5  fj.  long, 
a  middle  piece  5  or  6  //  long,  and  a 
tail  40  to  50  //  long.  The  head  is 
of  a  flattened  oval  or  pyriform  shape, 
to  the  large  end  of  which  the  middle 
piece  or  tail  is  attached.  The  middle  piece  is  a  cylindrical 
segment  more  or  less  distinctly  marked  off  from  the  tail.  The 
tail  is  a  long  fine  filament  or  flagellum,  tapering  to  a  point ;  it 
possesses  an  "axial  fibre"  surrounded  (except  for  a  short  dis- 


— d 


— e 


Human  spermatozoa  (Bohm  and 
Davidpff ).  The  left  figure  is  a 
side  view  ;  the  middle  figure 
a  top  view,  a,  head ;  6,  cen- 
trosome  (?) ;  c,  middle  piece  ; 
d,  sheath  about  axial  fibre  (e). 


182  THE  REPRODUCTIVE  SYSTEM. 

tance  at  the  end)  with  a  protoplasmic  sheath.  The  tail  ex- 
hibits rapid  vibratory  movements,  by  means  of  which  the 
spermatozoon  is  propelled  forward. 

Spermatozoa  are  real  cells,  though  of  unusual  type.  The 
head  is  of  the  nature  of  a  nucleus,  while  the  tail  and  a  pos- 
sible protoplasmic  envelope  about  the  head  may  be  taken  to 
be  cytoplasm.  The  chromosomes  are  "  reduced."  A  very 
minute  round  body  detected  by  some  observers  just  posterior 
to  the  head  is  perhaps  a  centrosome. 

FEMALE  GENITAL  ORGANS. 

The  female  genital  organs  are  the  ovaries,  oviducts,  uterus, 
vagina,  vulva,  vestiges  of  foetal  structures,  and  mammary 
glands.  The  pelvic  organs  are  developed  from  the  embryonic 
Wolffian  body  and  duct  of  Miiller  and  their  epithelium  is  of 
mesoblastic  origin. 

The   Ovary. 

The  ovary  (Fig.  71)  consists  of  a  connective-tissue  mass  or 
stroma,  in  which  are  imbedded  large  numbers  of  developing 

FIG.  71. 


Section  of  ovary  of  cat  (Schron).  1,  epithelial  covering;  1',  hilnm;  2,  medulla; 
8,  stroma  of  cortex ;  4,  bloodvessels ;  5,  undeveloped  ovisacs :  6,  7,  8,  developing 
Graafian  follicles;  9,  mature  Graafian  follicles;  10,  corpus  luteum. 

ova,  each  in  a  structure  called  an  ovisac  or  Graafian  follicle ; 
the  whole  organ  being  covered  by  an  epithelial   investment. 


OVA.  183 

The  ova  and  Graafian  follicles  occupy  the  peripheral  or  cor- 
tical portion  of  the  ovary  (the  "  oophoron  "),  leaving  in  the 
interior  a  medullary  region  continuous  with  the  hilum,  where 
the  vessels  enter. 

The  epithelial  covering  of  the  ovary  is  a  single  layer  of 
cuboidal  or  low  columnar  cells,  called  "  germinal  epithelium  " 
from  the  fact  that  the  ova  are  developed  from  it  during  fetal 
life.  This  epithelium  is  continuous  with  the  peritoneal  endo- 
thelium,  the  glistening  squamous  cells  of  the  latter  being 
here  replaced  by  columnar  cells  of  less  lustre. 

The  stroma  of  the  ovary  is  a  mass  of  connective  tissue, 
made  up  in  the  cortical  region  largely  of  fusiform  connective- 
tissue  cells  with  scanty  intercellular  elements.  On  the  surface, 
just  beneath  the  epithelial  covering,  this  tissue  is  condensed 
into  a  layer  called  the  tunica  albuginea,  continuous  and  inti- 
mately connected  with  the  stroma. 

The  medullary  region  and  hilum  contain  the  larger  vessels, 
imbedded  in  connective  tissue  of  a  more  ordinary  kind,  in 
which  fibrous  elements  are  more  abundant. 

Scattered  about  in  the  stroma  (more  abundantly  in  certain 
animals  than  in  the  human  species)  are  large  epithelioid  (?) 
cells,  the  interstitial  cells,  similar  to  those  of  the  testis.  The 
ovary  is  well  supplied  with  bloodvessels,  and  also  possesses 
lymphatics  and  nerves. 

The  ova  (called  ovules  before  impregnation),  which  occupy 
the  peripheral  zone  of  the  ovary,  originate  during  foetal  life 
from  processes  of  the  germinal  epithelium  which  grow  down- 
ward and  are  then  cut  off,  leaving  isolated  nodules  of  epithe- 
lial cells  in  the  stroma.  In  each  of  these  nodules  one  cell, 
destined  to  become  the  ovum,  enlarges,  while  the  other  ac- 
companying (indifferent)  epithelial  cells  form  a  capsule  about 
it  and  'develop  ultimately  into  the  tunica  granulosa  of  the 
mature  Graafian  follicle.  The  cortex  of  the  ovary  contains 
large  numbers  (estimated  by  some  observers  at  about  70,000 
in  both  ovaries)  of  these  primitive  ovisacs  imbedded  in  the 
stroma,  each  consisting  of  a  large  ovule  surrounded  by  a 
more  or  less  definite  envelope  of  small  epithelial  cells.  In 
the  course  of  ovulation  and  menstruation  these  primitive 
ovisacs  develop  as  Graafian  follicles,  and  successively  mature 
and  discharge  the  ovules  from  the  ovary,  leaving  the  remains 


184  THE  REPRODUCTIVE  SYSTEM. 

of  the  follicles  visible  for  a  time  as  corpora  lutea.  At  any 
one  time  the  active  ovary  exhibits  a  number  of  Graafian  fol- 
licles and  corpora  lutea  in  different  stages  of  development, 
along  with  a  large  number  of  undeveloped  ovisacs. 

Graafian  follicles  (or  vesicles)  :  As  the  primitive  ovisacs 
develop  they  enlarge  and  sink  deeper  into  the  ovary.  The 
fully  developed  Graafian  follicles  are  spherical  or  oval  cysts 
about  4  to  10  mm.  in  diameter.  Each  is  surrounded  by  a 
condensation  of  the  stroma  in  which  it  is  imbedded,  forming 
a  vascular  connective-tissue  investment  called  the  theca  fol- 
liculi;  this  is  usually  described  as  consisting  of  two  layers,  an 
outer,  called  the  tunica  fibrosa,  and  an  inner,  called  the  tunica 
propria.  The  theca,  be  it  noted,  is  not  really  a  part  of  the 
Graafian  follicle,  but  is  a  condensation  of  the  ovarian  stroma 
surrounding  it. 

The  outer  layer  of  the  follicle  proper,  lying  next  to  the 
tunica  propria,  is  the  membrana  or  tunica  granulosa,  com- 
posed of  a  few  layers  of  small  spheroidal  nucleated  epithelial 
cells.  This  tunic  encloses  a  large  cavity  which  is  filled  with 
an  albuminous  fluid,  the  liquor  folliculi. 

At  one  point  in  its  circumference  the  tunica  granulosa  is 
thickened,  having  a  mass  projecting  inward  composed  of  cells 
identical  with  those  which  make  up  the  tunic  elsewhere ;  this 
mass  or  heap  of  cells  is  called  the  discus  proligerus,  or 
cumulus  ovigerus.  Within  this  cumulus  the  ovule  is  im- 
bedded ;  the  cells  in  a  layer  immediately  surrounding  the 
ovule  are  columnar  and  arranged  in  a  radiating  manner,  form- 
ing the  corona  radiata. 

The  ovule,  or  ovum  (Fig.  72),  is  a  large  spherical  cell  about 
.2  mm.  in  diameter;  each  Graafian  follicle  contains  one  ovule, 
rarely  two  or  three.  The  wall  of  the  ovule  is  a  thin  clear 
hyaline  membrane,  showing  indistinct  radial  markings ;  it  is 
variously  called  the  vitelline  membrane,  zona  pellucida,  zona 
radiata,  and  oolemma.  The  cell-body  of  the  ovule,  or  vitellus, 
is  a  mass  of  protoplasm  infiltrated  with  fat-particles.  The 
nucleus  of  the  ovule  is  a  spherical  body,  often  called  the 
germinal  vesicle;  within  it  is  a  nucleolus,  the  germinal  spot. 

Ovulation :  The  Graafian  follicle,  when  mature,  makes  its 
way  to  the  surface  of  the  ovary,  causing  a  bulging  at  that 
point.  The  tissues  overlying  the  follicle  become  thinned, 


CORPORA   LUTE  A.  185 

and  finally  the  vesicle  ruptures,  permitting  the  ovule  to  escape 
from  the  ovary  and  pass  into  the  oviduct.  The  discharge  of 
an  ovule  in  this  manner  takes  place  regularly  and  periodically, 

FIG.  72. 


Human  ovule  and  its  surroundings  in  the  ovary  (Nagel).  a,  g,  vitelline  mem- 
brane (zona  pellucida  and  zona  radiata) ;  b,  c,  vitellus  or  cytoplasm  of  ovule ; 
d,  nucleus  or  germinal  vesicle  ;  e,  corona  radiata ;  /,  cells  of  cumulus  ovigerus. 

comprising  the  process  called  ovulation,  which  stands  in  a 
definite  relation  with  menstruation. 

Corpora  lutea :  The  ruptured  Graafian  follicle  after  ovula- 
tion undergoes  a  series  of  retrograde  changes,  the  resulting 
structure  being  called  a  corpus  hiteum. 

The  wound  or  cavity  of  the  emptied  Graafian  follicle 
becomes  filled  with  blood  from  the  ruptured  vessels,  and  the 
cells  of  the  tunica  granulosa  proliferate  abundantly.  From 
the  fatty  degeneration  of  cells  or  the  transformation  of  haemo- 
globin into  haematoidin  the  structure  acquires  a  yellow  color, 
whence  its  name.  Into  the  mass  of  epithelial  cells  and  blood- 
clot  grow,  from  the  ovarian  stroma,  vascular  processes  of 
connective  tissue  (granulations),  giving  the  body  a  lobed  or 
radiate  appearance.  By  the  continued  growth  and  contrac- 


186  THE  REPRODUCTIVE  SYSTEM. 

tion  of  the  connective  tissue,  forming  a  sort  of  scar  or  cicatrix, 
the  corpus  luteum  is  finally  obliterated. 

The  whole  process  is  similar  to  that  by  which  wounds  in 
general  undergo  repair. 

The  corpora  lutea  which  result  when  the  discharged  ovules 
are  fecundated  (the  so-called  "true"  corpora  lutea)  attain  a 
larger  size  and  continue  in  existence  a  much  longer  time  (for 
many  months)  than  do  those  (the  "  false "  corpora  lutea) 
when  pregnancy  does  not  result. 

Obgenesis  :  The  ovary  is  similar  in  development  to  the  testicle  and 
complementary  to  it  in  function.  Both  are  organs  of  high  vital 
importance,  being  the  essential  genital  glands  and  seats  of  repro- 
duction. 

The  observations  made  above  with  respect  to  spermatogenesis 
apply  also,  mutatis  mutandis,  to  oogenesis,  the  development  of  ovules. 

The  ovary,  like  the  testicle,  has  an  ample  blood-supply  and  a  less 
conspicuous  innervation.  These  two  channels,  circulatory  and  nervous, 
are  the  only  apparent  means  of  communication  by  which  conditions 
in  other  parts  of  the  maternal  body  can  influence  the  ovary  and 
hence  be  transmitted  to  the  offspring.  That  the  ovary  can  in  such 
way  act  in  sympathy  with  organs  not  directly  connected  with  it 
is  shown  by  the  relations  between  ovulation,  menstruation,  and 
pregnancy. 

As  to  the  transmission  of  racial  and  hereditary  characteristics  from 
the  ovum  of  one  generation  to  the  ovules  of  the  next  through  a  suc- 
cession or  continuity  of  special  germ-cells,  the  same  considerations 
apply  in  oogenesis  as  in  spermatogenesis.  Some  differences  in  action 
of  the  female  and  male  genital  glands  may  be  noticed.  All  the  ovules 
discharged  by  the  human  female  exist  in  the  ovary  preformed  from 
birth ;  consequently  any  acquired  characters  in  the  mother,  if  trans- 
mitted to  offspring,  would  have  to  be  impressed  upon  cells  already 
formed  rather  than  upon  cells  to  be  subsequently  developed.  The 
spermatozoa  and  spermatogenic  cells,  on  the  contrary,  are  being 
continually  renewed  and  developed  de  novo.  Of  all  the  primitive 
ovules  in  the  ovaries  only  a  few  hundred  come  to  maturity  in  the  life- 
time of  the  human  female ;  in  contrast  to  this  the  male  produces  and 
disseminates  millions  of  spermatozoa. 

The  oviducts,  or  Fallopian  tubes,  are  conical  tubes  opening 
into  the  uterus  by  the  small  end  and  into  the  peritoneal  cavity 
by  the  large  end,  which  is  fimbriated.  The  wall  of  the  ovi- 
duct consists,  from  within  outward,  of  mucous,  submucous, 
muscular,  and  serous  coats.  The  mucous  coat  is  formed  by  a 
single  layer  of  columnar  ciliated  epithelium-cells  resting  on  a 
firm  tunica  propria.  At  the  margins  of  the  fimbria3  the 


UTERINE  MUCOUS  MEMBRANE.  187 

ciliated  cells  meet  the  squamous  endothelium -cells  lining  the 
peritoneum.  The  mucosa  is  thrown  into  broad  folds  or 
plications,  mostly  branching,  which  project  radially  into  the 
lumen  of  the  tube.  Between  the  mucosa  and  submucosa  is  a 
thin  layer  of  involuntary  muscle  representing  a  muscularis 
mucosae.  The  submucous  coat  is  made  up  of  areolar  tissue 
containing  the  larger  vessels.  The  oviducts  contain  no  glands. 
Outside  the  submucous  coat  is  a  muscular  coat,  composed  of  a 
thick  inner  circular  layer  and  a  thinner  outer  longitudinal 
layer  of  involuntary  muscle.  The  outermost  or  serous  cover- 
ing of  the  oviduct  is  formed  by  the  peritoneum  and  subperi- 
toneal  tissue. 

Remnants  of  foetal  structures :  The  parovarium  is  a  series 
of  tubules  lined  with  simple  columnar  epithelium,  situ- 
ated in  the  broad  ligament  near  the  hilum  of  the  ovary 
and  between  the  latter  and  oviduct;  they  are  remains  of 
tubules  of  the  embryonic  Wolffian  body.  Other  similar 
tubules,  which  have  received  special  names,  are  also  sometimes 
found  in  the  broad  ligament.  Pedunculated  hydatids  (hydatids 
of  Morgagni),  small  epithelial  sacs,  are  sometimes  attached  to 
the  ovary,  parovarium,  or  a  h'mbria  of  the  oviduct. 

The  Uterus. 

The  uterus  is  a  hollow,  muscular  organ,  the  wall  of  which 
is  composed  chiefly  of  involuntary  muscle,  lined  internally 
by  mucous  membrane  and  externally  by  serous  membrane 
(Fig.  73). 

The  uterine  mucous  membrane  consists  of  epithelium  resting 
on  a  tunica  propria  which  contains  numerous  tubular  glands. 
The  epithelium  lining  the  uterus  is  a  single  layer  of  short 
columnar  or  cuboidal  ciliated  cells.  The  tunica  propria  is  a 
layer  of  connective  tissue  of  an  embryonal  or  growing  type, 
containing  fusiform  connective-tissue  cells  and  lymphoid  cells 
or  leukocytes  in  abundance,  with  scanty  intercellular  ele- 
ments; it  contains  abundant  bloodvessels,  extends  downward 
to  the  muscular  coat,  and  in  it  are  imbedded  the  uterine 
glands. 

The  embryonic  character  of  the  connective  tissue  of  the 
tunica  propria  is  apparently  due  to  the  fact  that  the  latter  in 


188 


THE  REPRODUCTIVE  SYSTEM. 


the  course  of  menstruation  is  at  short  intervals  cast  off  and 
grows  anew. 

The  uterine  glands  are  numerous  tubular  glands,  mostly 
simple  and  unbranched,  extending  perpendicularly  from  the 
surface  of  the  mucosa  to  the  muscular  coat.  Their  deeper 
portions  are  convoluted,  their  superficial  portions  more 


FIG.  73. 


Section  throrugh  wall  of  a  rabbit's  \iterus  (Schiifer).    m,  mucosa  (the  cilia  of  the 
epithelium  are  not  shown) ;  a,  muscular  coat ;  s,  peritoneum. 

straight.  They  are  lined  by  a  continuation  of  the  simple 
ciliated  epithelium  of  the  mucous  surface.  Their  function  is 
not  so  much  secretory  as  to  serve  as  foci  for  the  regeneration 
of  the  epithelium  after  menstruation. 

The  muscular  coat  makes  up  the  bulk  of  the  uterine  sub- 
stance.    It   consists  of   layers   and    fasciculi  of  non-striated 


PREGNANCY.  189 

muscle,  imbedded  in  connective  tissue  and  intermingled  with 
numerous  large  arterial  and  venous  channels.  The  muscular 
tissue  is  arranged  in  general  in  three  strata,  an  inner  and  an 
outer  longitudinal  and  a  middle  circular  layer ;  but  these 
divisions  are  not  very  distinct  and  the  arrangement  is  not  very 
definite. 

The  outer  surface  of  the  uterus  is  covered  with  serous  mem- 
brane, consisting  of  the  folds  of  the  peritoneum  reflected  over 
it.  The  bloodvessels  of  the  uterus  are  unusually  large, 
abundant,  and  tortuous. 

The  cervix  of  the  uterus  has  a  thicker  mucosa,  which  is 
thrown  into  rugae,  and  a  more  regular  arrangement  of  the 
three  muscle-layers  than  the  body  of  the  organ. 

The  upper  portion  of  the  cervical  canal  is  covered  with 
simple  ciliated  epithelium  ;  but  the  loiter  poiiion  is  lined  with 
stratified  squamous  epithelium,  and  the  underlying  tunica 
propria  presents  numerous  projecting  papillae. 

In  the  lower  part  of  the  cervix  mucous  glands  are  present, 
in  addition  to  the  uterine  glands.  From  the  closure  of  their 
outlet-ducts  these  mucous  glands  often  become  distended  with 
secretion,  forming  small  cysts  called  ovula  of  Naboth.  The 
outer  surface  of  the  cervix  uteri  is  lined  by  the  vaginal 
mucous  membrane. 

During  menstruation  the  mucous  lining  of  the  uterus  be- 
comes much  thickened  ;  the  epithelium  cells  swell,  the  tunica 
propria  becomes  very  vascular  and  increases  in  thickness,  and 
the  uterine  glands  enlarge.  The  mucosa  becomes  softened 
and  degenerated,  and  is  finally  cast  off,  mingled  with  blood, 
as  the  menstrual  discharge.  After  menstruation  is  over  the 
mucous  membrane  is  rapidly  renewed,  the  surface  epithelium 
being  regenerated  from  the  portions  of  the  uterine  glands 
remaining  in  the  depths  of  the  tunica  propria. 

During  pregnancy  there  is  a  great  hypertrophy  or  increased 
development  of  the  mucous  and  muscular  coats  and  the  vascu- 
lar system  of  the  uterus.  The  mucosa  undergoes  special 
changes  and  to  it  become  attached  the  placenta  and  foatal  en- 
velopes; it  exhibits  fusiform  connective-tissue  cells,  large 
numbers  of  decidual  cells  (large  brown  pigmented,  round,  or 
polymorphous  cells,  sometimes  multinucleated),  dilated  and 
compressed  lumina  of  the  uterine  glands,  and  an  increase  of 


190  THE  REPRODUCTIVE  SYSTEM. 

vascular  channels,  while  the  superficial  and  glandular  epithe- 
lium becomes  disintegrated  or  much  altered.  Its  inner  surface 
becomes  intimately  connected  with  the  placenta  and  the  chorion. 
Two  layers  are  distinguished  in  the  mucosa,  a  superficial 
"compact  layer'7  and  a  deeper  "cavernous"  or  "spongy 
layer"  ;  the  latter  lies  next  to  the  muscular  wall  of  the  uterus, 
and  is  characterized  by  containing  the  distended  deeper  por- 
tions of  the  uterine  glands. 

This  specially  developed  mucosa  of  the  pregnant  uterus  is 
called  the  decidua,  and  is  cast  off  with  the  placenta  and  mem- 
branes at  the  birth  of  the  foetus.  The  decidua  exhibits  three 
divisions :  the  decidua  serotina,  which  enters  into  the  forma- 
tion of  the  placenta  ;  the  decidua  vera,  which  lines  the  non- 
placental  portion  of  the  inner  surface  of  the  uterus,  and  is 
cast  off,  united  to  the  chorion,  as  part  of  the  foetal  membranes  ; 
and  the  decidua  reflexa,  which  in  the  early  part  of  pregnancy 
grows  out  from  the  mucosa  into  the  cavity  of  the  uterus  and 
surrounds  the  ovum  and  foetus,  but  at  a  later  period  degener- 
ates and  disappears.  After  labor  takes  place  the  hypertro- 
phied  uterus  undergoes  retrogressive  changes  and  involution 
to  its  ordinary  size,  and  its  mucous  lining  is  regenerated  from 
the  remnants  of  the  tunica  propria  and  epithelium  left  after 
the  casting  off  of  the  decidua. 

Foetal  Appendages. 

The  primitive  appendages  of  the  foetus  are  the  amnion,  chorion, 
allantois,  and  umbilical  vesicle,  all  derived  from  the  embryo,  together 
with  the  decidua,  which  is  of  uterine  origin.  The  umbilical  vesicle  is 
a  rudimentary  structure  and  soon  disappears.  The  amnion,  chorion, 
and  decidua  form,  in  general,  from  within  outward,  three  envelopes 
about  the  foetus.  As  fully  developed,  at  term,  these  structures  form  the 
"after-birth"  or  "  secundines,"  consisting  of  the  foetal  membranes,  the 
placenta,  and  the  umbilical  cord ;  these  are  delivered  with  the  foetus 
at  birth. 

The  (internal  or  true)  amnion,  the  innermost  foetal  envelope,  is  a 
thin  membranous  closed  sac  filled  with  fluid  in  which  the  foetus  is  im- 
mersed. It  originates  as  an  outgrowth  from  the  embryo,  and  consists 
of  two  layers,  the  innermost  (toward  the  foetus)  an  epithelial  and  epi- 
blastic  layer ;  the  outer,  a  mesoblastic  (somatopleural)  connective-tissue 
layer.  It  is  at  first  separate  from  the  chorion,  but  afterward  becomes 
united  to  it  and  lines  the  inner  free  surface  of  the  foetal  membranes  and 
placenta. 

The  chorion,  the  middle  envelope,  in  man  originates  chiefly  from  the 


FCETAL  MEMBRANE.  191 

external  or  "false"  amnion  (composed  of  epiblast  and  somatopleure) 
and  over  a  small  area  from  the  allantois — besides  the  vitelline  mem- 
brane of  the  ovum,  which  early  disappears.  The  chorion  exhibits 
externally  (toward  the  uterine  wall)  an  epiblastic  epithelial  layer,  de- 
rived from  the  external  amnion  ;  and  internally  a  connective-tissue 
layer  of  mesoblastic  origin,  derived  from  the  amnion  and  allantois. 
The  chorion  is  connected  with  the  foetus  by  a  vascular  mesoblastic  stalk 
(the  umbilical  cord)  made  up  mainly  of  the  allantois. 

The  allantois  is  a  saccular  outgrowth  from  the  primitive  intestine, 
extending  to  the  chorion  and  uniting  with  the  latter  over  a  greater  or 
less  area.  It  consists  of  mesoblast  (splanchnopleure)  externally  and 
internally  has  a  cavity  lined  with  hypoblast ;  in  man  the  portion  of 
the  allantoic  cavity  beyond  the  abdominal  wall  consists  only  of  a  small 
tube  extending  into  the  umbilical  cord.  The  umbilical  bloodvessels 
are  derived  from  the  allantois.  The  mesoblastic  tissues  of  the  allantois 
enter  into  the  formation  of  the  chorion  and  umbilical  cord. 

At  a  very  early  period  numerous  vascular  tufts,  chorial  villi,  grow 
out  from  the  chorion  on  all  sides,  projecting  toward  the  uterine  wall. 
A  portion  of  the  chorion,  called  the  "  chorion  frondosum,"  enters  into 
the  formation  of  the  placenta,  the  villi  of  this  region  undergoing  great 
development  and  becoming  intimately  united  with  the  corresponding 
portion  of  the  decidua  (the  decidua  serotina).  Over  the  remainder  of 
the  choriou,  the  "  chorion  laeve,"  the  villi  disappear,  this  portion  of 
the  chorion  becoming  united  with  the  decidua  vera  to  form  (with  the 
amnion)  the  foetal  membranes. 

The  decidua,  already  described,  is  the  modified  uterine  mucosa  in 
three  divisions — the  serotina,  vera,  and  reflexa. 

The  umbilical  vesicle,  or  "  yolk  sac,"  in  the  higher  mammals  has 
little  functional  value,  and  soon  disappears.  It  consists  of  a  sac  or 
vesicle  situated  between  the  amnion  and  chorion,  and  a  pedicle  or 
stalk  in  the  umbilical  cord.  In  origin  it  is  continuous  with  the  primi- 
tive intestine,  and  consists  of  a  vascular  mesoblastic  (splanchnopleural) 
layer  externally,  and  is  lined  with  hypoblast  internally. 

The  foetal  membrane  ("  bag  of  waters  ")  is  a  thin,  translucent  mem- 
brane given  off  from  the  margin  of  the  placenta,  forms  a  closed  sac 
about  the  foetus,  and  is  closely  applied  to  the  inner  surface  of  the 
uterus.  It  is  filled  with  a  quantity  of  serous  fluid,  the  liquor  amnii, 
in  which  the  foetus  is  immersed.  It  is  formed,  from  within  outward, 
of  the  amnion,  chorion,  and  decidua  vera. 

The  amnion  is  a  thin,  non-vascular  membrane,  lined  on  its  free  sur- 
face (that  directed  toward  the  foetus)  by  simple  squamous  epithelium, 
beneath  which  is  a  connective-tissue  stratum  composed  of  connective- 
tissue  cells  (chiefly  flat,  stellate  or  irregular,  many  with  anastomosing 
processes),  fibres,  and  gelatinous  intercellular  substance.  In  places  the 
outer  surface  exhibits  small  hexagonal  endothelioid  cells.  The  amnion 
is  loosely  connected  with  the  underlying  chorion  by  fibrous  strands, 
or  very  delicate  muco-fibrous  tissue,  so  that  it  has  some  play  over  the 
latter  and  can  be  stripped  off. 

The  liquor  amnii,  which  surrounds  the  foetus  and  fills  the  amniotic 
sac,  is  a  serous  fluid  holding  proteid  and  other  substances  in  solution. 


192  THE  REPRODUCTIVE  SYSTEM. 

The  chorion,  the  middle  constituent  of  the  foetal  membrane,  exhibits 
two  layers,  an  inner  fibrous  and  an  outer  cellular  layer.  The  fibrous 
layer  is  next  to  the  amnion,  with  which  it  is  loosely  united  ;  it  is  of 
mesoblastic  origin  and  composed  of  fibrous  tissue.  The  outer  or  "  cel- 
lular layer  "  consists  of  several  layers  of  large  spheroidal  prominently 
nucleated  cells,  apparently  of  epiblastic  origin  and  epithelial  nature. 

Externally  the  chorion  is  closely  united  to  the  decidua  vera  (the 
decidua  reflexa  degenerating  and  disappearing  by  about  the  seventh 
month) ;  the  decidua  vera,  the  mucosa  of  the  pregnant  uterus,  at  labor 
is  cast  off  with  the  foetal  membrane  as  its  outermost  lamina. 

The  placenta  is  formed  by  the  union  of  the  chorion  frondosum  and 
xiecidua  serotina,  and  hence  consists  partly  of  foetal  and  partly  of 
maternal  tissues.  It  is  essentially  an  intimate  interlacement  of  foetal 
and  maternal  blood-channels,  serving  alimentary,  respiratory,  and 
excretory  purposes  for  the  foetus.  The  placenta  consists  of  four  layers, 
which  are,  from  the  foetal  surface  outward,  the  amnion,  the  chorion,  a 
broad  layer  of  chorial  villi  separated  by  maternal  blood-sinuses,  and 
the  decidua  serotina. 

The  portion  of  the  amnion  lining  the  foetal  surface  of  the  placenta  is 
continuous  with  that  lining  the  foetal  membranes,  and  is  similar  to  the 
latter  in  its  structure,  having  a  superficial  epithelial  and  deeper  con- 
nective-tissue layer,  and  being  connected  with  the  chorion  by  delicate 
muco-fibrous  tissue. 

The  placental  portion  of  the  chorion  (chorion  frondosum)  presents 
toward  the  amnion  a  fibrous  layer,  and  beneath  this  the  epithelioid 
"cellular  layer,"  as  in  the  chorion  Iseve,  with  which  it  is  continuous; 
beneath  the  cellular  layer  is  a  coagulum-like  stratum  containing  pas- 
sages and  spaces,  called  the  "  canalized  fibrin." 

The  substance  of  the  placenta  is  composed  of  a  mass  of  "chorial 
villi,"  with  intervening  maternal  blood-spaces,  interposed  between  the 
chorion  and  decidua  serotina.  On  following  the  foetal  membranes  into 
the  margin  of  the  placenta,  the  chorion  and  decidua  separate,  the 
interval  between  them  being  filled  with  the  villi  and  sinuses.  The 
umbilical  vessels  on  reaching  the  placenta  divide  and  subdivide  and 
spread  over  its  surface,  running  in  the  fibrous  layer  of  the  chorion. 
The  branches  of  these  vessels  pass  outward  from  the  chorial  mem- 
brane, toward  the  uterine  wall,  forming  branching  vascular  tufts,  the 
chorial  villi,  which  are  covered  with  an  epithelioid  investment  from 
the  outer  epiblastic  layer  of  the  chorion. 

The  villi  begin  as  large  coarse  trunks  passing  from  the  chorion 
toward  the  decidua;  these  divide  into  a  great  profusion  of  small 
cylindrical  branches  and  twigs.  The  ends  of  some  of  the  villi  become 
attached  to  the  decidua  serotina,  but  most  of  the  branches  end  in  free 
or  floating  blunt,  round  extremities.  The  villi  are  composed  of  arterial 
and  venous  channels  and  capillary  loops,  imbedded  in  a  loose  connec- 
tive tissue,  with  their  surface  covered  with  tissue  of  epithelial  origin. 
The  foetal  vessels  are  closed,  and  nowhere  open  into  the  maternal 
blood-channels. 

The  epithelioid  tissue  lining  the  surface  of  the  villi  consists  variously 
of  distinct  cells,  a  protoplasmic  lamina  containing  numerous  nuclei, 


VAGINA.  193 

or  projecting  clusters  of  cells ;  this  epithelioid  investment  is  derived — 
its  deeper  part  at  least — from  the  epiblastic  outer  layer  of  the  chorion  ; 
partly  also,  perhaps,  from  the  epithelium  of  the  uterine  mucosa.  The 
twigs  of  the  villi  are  separated  by  open  spaces,  "  intervillous  spaces," 
into  which  the  maternal  arteries  and  veins  in  the  decidua  open 
directly;  these  spaces  thus  form  an  extensive  system  of  blood-sinuses, 
filled  with  maternal  blood,  into  which  the  chorial  villi  project.  By 
interchanges  between  the  foetal  blood  circulating  in  the  villi  and  the 
maternal  blood  which  surrounds  the  villi  the  alimentary  and  excretory 
needs  of  the  foetus  are  provided  for. 

The  decidua  serotina,  which  is  continuous  with  the  decidua  vera, 
forms  the  deepest  stratum  of  the  placenta ;  it  is  a  thin  lamina,  and 
has  been  already  described  as  the  mucosa  of  the  pregnant  uterus. 
Among  its  constituents  the  abundant  "  decidual  cells "  are  notable. 
Septa  from  the  decidua  pass  part  way  into  the  placenta  and  divide  it 
into  lobes  or  cotyledons.  At  the  margin  of  the  placenta  these 
septa  mav  reach  the  chorion  and  form  in  places  a  "  subchorial  decidual 
layer." 

The  umbilical  cord  is  a  vascular  cord  connecting  the  foetus  with  the 
placenta.  It  is  formed  by  the  stalk  of  the  chorion  and  allantois, 
covered  on  the  surface  by  the  amnion.  It  consists  of  two  arteries  and 
one  vein,  twisted  spirally,  surrounded  by  gelatinous  embryonic  or 
young  connective  tissue  ("  Wharton's  jelly"),  and  lined  superficially 
with  epithelium.  The  epithelium  covering  the  surface  of  the  cord  is 
of  the  squamous  variety,  stratified  or  simple,  and  is  continuous  with 
the  epithelium  lining  the  amnion,  also  with  the  foetal  epidermis. 

In  the  earlier  part  of  pregnancy  the  jelly  of  Wharton  or  connective 
tissue  surrounding  the  umbilical  vessels  is  a  mucous  tissue,  composed 
of  anastomosing  mucous  cells  with  the  meshes  and  interstices  between 
them  filled  with  a  soft  mucinous  or  gelatinous  intercellular  substance; 
toward  the  close  of  pregnancy  fibrous  elements  develop  abundantly  in 
the  interstices  of  this  tissue.  The  umbilical  vessels  possess  thick  walls, 
made  up  mainly  of  laminae  of  involuntary  muscle-cells  arranged  longi- 
tudinally, obliquely,  and  transversely ;  elastic  fibres  are  scanty  in  the 
vessel-walls,  and  the  ad ventitia  merges  into  the  surrounding  Wharton's 

Jell.v- 

At  an  early  period  the  cord  also  contains  the  cavity  of  the  allantois 
and  the  stalk  of  the  umbilical  vesicle,  both  being  tubules  lined  with 
hypoblast ;  these  structures  later  disappear,  though  traces  of  them 
may  sometimes  remain  visible  as  columns  or  canals  of  epithelioid  cells. 

The  vagina :  The  walls  of  the  vagina  are  composed  of 
mucous,  submucous,  muscular,  and  fibrous  layers,  from  within 
outward.  The  inner  surface  is  disposed  in  transverse  rugae. 
The  mucosa  consists  of  stratified  squamous  epithelium  resting 
on  a  tunica  propria.  The  latter  contains  abundant  elastic 
fibres  and  diffuse  lymphoid  tissue,  and  its  surface  exhibits 
papillae  projecting  into  the  epithelial  layer.  No  glands  are 

13— Hist. 


194  THE  REPRODUCTIVE  SYSTEM. 

present.  The  submncosa  is  a  layer  of  loose  connective  tissue 
containing  rich  vascular  plexuses,  a  sort  of  erectile  tissue. 
The  muscular  coat  consists  in  general  of  an  inner  circular 
and  an  outer  longitudinal  layer  of  involuntary  muscle.  The 
outermost  coat  is  fibrous,  or  areolar,  connecting  the  vagina 
with  the  bladder  anteriorly  and  with  the  peritoneum,  rectum, 
and  perineum  posteriorly.  Among  the  nervous  elements  of 
the  vagina  are  special  sensory  terminals. 

The  vulva  is  covered  with  an  integument  continuous  with 
the  mucous  membrane  of  the  vagina  and  urethra  and  with 
the  external  skin.  This  integument  consists  of  stratified 
squamous  epithelium,  in  places  pigmented,  resting  on  a  papil- 
lated  tunica  propria,  beneath  which  is  a  loose  areolar  sub- 
mucous  layer. 

Opening  on  the  surface  are  numerous  small  glands,  both 
mucous  and  sebaceous ;  the  latter  occur  not  only  on  the  hairy 
portions  of  the  labia  majora,  but  also  on  the  iabia  minora 
unassociated  with  hairs. 

The  glands  of  Bartholin  are  two  macroscopic  racemose 
glands,  corresponding  to  Cowper's  glands  of  the  male,  situated 
in  the  labia  minora,  one  on  each  side  of  the  outlet  of  the 
vagina.  Special  sensory  nerve-terminals  occur  in  the  mucous 
membrane  in  this  region. 

Beneath  the  integument  of  the  labia  majora  are  masses  of 
adipose,  areolar,  vascular,  and  muscular  tissue ;  beneath  that 
of  the  labia  minora  and  vestibule  is  an  especial  abundance  of 
vascular  plexuses  and  sinuses,  forming  an  erectile  tissue.  In 
the  deeper  strata  of  the  genitalia  are  fasciculi  of  muscle,  both 
striated  and  non-striated,  variously  arranged. 

The  hymen  is  a  fold  of  the  vaginal  mucous  membrane. 
The  clitoris  repeats  in  a  rudimentary  way  the  cavernous  and 
erectile  structure  of  the  penis. 

The  Mammary  Glands. 

The  mammary  glands  are  fully  developed  only  during  their 
periods  of  functional  secreting  activity,  the  periods  of  lacta- 
tion; at  other  times  they  are  in  an  atrophic  non-secreting 
condition. 

When  in  the  state  of  active  secretion  the  mammary 


SUSTENTACULAR   CONNECTIVE  TISSUE. 


195 


is  a  compound  racemose  gland,  of  the  fatty  type  (secreting 
also  a  serous  and  albuminous  fluid),  and  is  situated  in  the 
subcutaneous  tissue.  It  is  divided  by  septa  into  fifteen  to 


FIG.  74. 


Secreting  alveoli  of  mammary  gland  of  guinea-pig  during  lactation  (Michaelis). 

twenty  lobes,  and  these  again  into  lobules,  each  of  which  is 
made  up  of  a  number  of  the  ultimate  alveoli  (Fig.  74). 

Each  of  the  lobes  has  a  separate  outlet-duct  opening  at  the 
nipple,  each  lobe  thus  being  essentially  a  distinct  gland. 

The  sustentacular  connective  tissue  consists  of  interlobar 
septa,  interlobular  septa,  and  a  small  amount  of  interalveolar 
connective  tissue  lying  between  the  alveoli.  Adipose  and 
areolar  tissue  is  also  abundant,  filling  the  intervals  between 
the  lobes  and  lobules. 

The  ultimate  secreting  alveoli  are  large  oval  or  elongated 
saccules,  with  large  open  lumina,  and  are  lined  with  a  layer 
of  granular  spheroidal  epithelium-cells,  which  secrete  the 
milk.  Within  these  cells  globules  of  oil  develop  and  are 
discharged  into  the  lumen  to  form  the  fat-particles  of  the 
secreted  milk. 

The  alveoli  empty  into  ducts,  called  lactiferous  or  galac- 


196  THE  REPRODUCTIVE  SYSTEM. 

tophorous  ducts,  which  are  lined  with  a  layer  of  low  columnar 
epithelium  and  gradually  increase  in  size  as  they  unite.  The 
ducts  in  each  lobe  unite  to  form  a  large  outlet-duct,  which 
pursues  a  separate  course  to  the  nipple,  distinct  from  the  other 
lobar  ducts.  These  large  lobar  outlet-ducts  have  well-marked 
walls  of  fibrous  tissue  and  some  unstriped  muscle ;  toward 
the  nipple  they  are  dilated  so  as  to  form  ampullce  or  sinuses, 
which  serve  as  temporary  receptacles  for  the  milk,  and  open 
at  the  nipple  by  constricted  orifices;  they  are  lined  with 
simple  columnar  epithelium  nearly  to  the  nipple,  where  the 
lining  changes  to  stratified  squamous. 

The  nipple  is  covered  with  a  sort  of  mucous  membrane, 
rosy  or  pigmented,  lined  with  stratified  squamous  epithelium, 
and  containing  numerous  special  sensory  nerve-terminals. 
Within  the  nipple  is  involuntary  muscle,  to  which  its  erec- 
tility  is  due.  Scattered  about  the  base  of  the  nipple  and  the 
surrounding  areola  are  the  small  racemose  glands  of  Mont- 
gomery, especially  developed  during  lactation,  which  corre- 
spond to  small  projections  on  the  surface. 

When  not  in  a  condition  of  active  secretion,  the  alveoli  are 
smaller,  less  numerous,  rudimentary  or  atrophic ;  instead  of 
having  a  cavity  their  lumen  is  filled  with  cells,  so  that  they 
are  represented  by  small  solid  nodules  of  epithelium. 

The  system  of  ducts  is  present  and  well  formed. 

Areolar  and  adipose  tissue  is  more  abundant,  taking  the 
place  of  the  undeveloped  or  degenerated  alveoli,  which  are 
imbedded  in  this  increased  amount  of  connective  tissue. 

Such  is  the  rudimentary  and  undeveloped  structure  of  the 
mamma  in  females  before  the  first  pregnancy,  and  in  males. 

During  pregnancy  the  gland  undergoes  active  development, 
especially  the  secretory  alveoli,  which  increase  in  number  and 
size,  while  the  intervening  connective  tissue  is  reduced,  and 
the  cells  in  the  centre  of  the  solid  alveolar  epithelial  masses 
undergo  fatty  degeneration  and  at  the  beginning  of  lactation 
are  perhaps  cast  oif  in  the  first  milk  as  colostrum-corpuscles. 

After  lactation  is  over  the  gland  undergoes  retrogressive 
changes  or  involution  to  its  former  condition,  the  alveoli 
atrophying  and  being  replaced  by  adipose  and  areolar  tissue. 

Milk,  the  secretion  of  the  mammary  gland,  consists  micro- 


THE  ADRENAL   OR  SUPRARENAL   GLANDS.         197 

scopicallv  of  a  homogeneous  transparent  liquid  in  which  are 
suspended  large  numbers  of  minute  round  or  oval  globules 
of  fat,  varying  in  size  from  two  to  five  /A  These  globules 
cause  the  opacity  and  white  color  of  the  milk  ;  they  are  sup- 
posedly surrounded  and  kept  intact  by  albuminous  (casein) 
envelopes. 

The  milk  secreted  at  the  beginning  of  lactation,  the  colos- 
trum, contains,  in  addition  to  the  constituents  of  ordinary 
milk,  larger  spherules  of  fat  and  colostrum-corpuscles.  The 
latter  are  large  cells  filled  with  particles  of  fat,  and  are  re- 
garded by  some  as  epithelium-cells;  by  others,  as  wandering 
cells  which  have  undergone  fatty  degeneration. 


CHAPTER    XV. 

MUSCULAR  AND  SKELETAL  STRUCTURES. 

IN  a  logical  analysis  of  the  systems  of  the  body,  the  motor 
structures  (voluntary)  and  the  framework  of  the  body  deserve 
equal  and  coordinate  rank  and  consideration  with  the  other 
systems.  The  elemental  tissues  which  make  up  the  greatest 
part  of  the  muscular  and  skeletal  structures  have,  however, 
been  already  described  (Chapter  IV.),  so  that  only  a  few  fur- 
ther points  need  attention. 

The  voluntary  muscles  are  made  up  of  striated  muscle-cells 
or  fibers,  united  by  sustentacular  connective  tissue  into  fas- 
ciculi, and  these  again  into  entire  muscles.  They  are  richly 
supplied  with  capillaries.  That  portion  of  the  sustentacular 
tissue  enveloping  the  entire  muscle  is  called  the  epimysium ; 
that  investing  the  several  fasciculi  is  the  per imy slum  ;  the  deli- 
cate connective  tissue  within  the  fasciculi,  among  the  indi- 
vidual muscle-cells,  is  the  endomysium. 

Tendons  consist  of  white  connective-tissue  fibres  cemented 
together  in  parallel  non-vascular  dense  bundles  ;  these  are 
bound  together  into  entire  tendons  by  trabeculse  and  sheaths 
of  sustentacular  tissue,  which  contains  the  vascular  supply. 
In  rows  between  the  white  fibres  are  the  tendon-cells,  special- 
ized connective-tissue  cells ;  they  send  flat  lamellar  projections 
between  adjacent  fibres,  thus  having  a  rectangular  appearance 
from  the  side,  stellate  in  cross-section.  The  nuclei  of  adjoin- 
ing cells  are  often  situated  near  each  other,  forming  pairs. 
The  surface  of  tendons  is  often  lined  with  endothelium. 

The  connection  between  the  tendons  and  the  muscle-cells  is 
in  general  established  by  the  fibres  of  the  endomysium  ;  these 
are  united  on  the  one  hand  to  the  sarcolemma  at  the  extremi- 
ties of  the  muscle-cells,  and  on  the  other  are  connected  with 
tendon-fibres.  At  the  junction  of  muscles  and  tendons  their 
connective-tissue  elements  are  continuous  and  merge  into 
each  other. 

198 


TEND  ON-SHEA  THS.  199 

Tendons  and  ligaments  at  their  insertion  into  bones  become 
intimately  blended  with  the  periosteum,  and  their  fibres  often 
meet  the  bony  substance  obliquely  or  perpendicularly.  Some 
of  the  fibres  penetrate  the  bone  for  a  short  distance  after  the 
manner  of  Sharpey's  fibres,  so  that  the  osseous  tissue  and  the 
tendon-fibres  dovetail  into  each  other,  affording  a  very  firm 

FIG.  75. 


Cross-section  of  portion  of  tendon  (Schafer). 

union.  These  fibrous  insertions  can  be  stripped  from  the 
bone  only  with  difficulty,  more  so  than  the  periosteum  else- 
where, and  the  surface  of  the  denuded  bone  at  such  points  is 
rough  and  uneven. 

Synovial  membranes,  allied  to  serous  membranes,  are  thin 
fibrous  membranes  more  or  less  completely  covered  on  their 
free  surface  with  flat  connective-tissue  or  endothelium  cells. 
They  form  sheaths  or  sacs  in  connection  with  moving  surfaces, 
of  three  kinds — articular,  vaginal,  and  bursal.  The  arricular 
synovial  membranes  inclose  joints  ;  the  vaginal  form  tendon- 
sheaths  ;  the  bursal  line  the  bursse.  They  secrete,  by  a  sort 
of  glandular  action,  a  glairy  fluid  which  lubricates  the  opposed 
surfaces  that  move  on  each  other. 

Tendon-sheaths :  The  tendons  in  some  situations,  in  the 
vicinity  of  joints,  notably  in  the  hand  and  foot,  are  sur- 


200          MUSCULAR  AND  SKELETAL  STRUCTURES. 

rounded  by  synovial  sheaths  or  sacs  in  which  they  smoothly 
glide. 

Bursae  are  small  synovial  sacs  situated  at  points  exposed  to 
friction ;  they  facilitate  movement  by  the  gliding  of  their 
opposite  surfaces  over  each  other,  lubricated  by  their  glairy 
contents.  They  occur  at  exposed  points  underneath  the  skin, 
as  over  the  patella,  and  interposed  between  tendons  and  bones, 
as  over  the  bicipital  tuberosity  of  the  radius. 

The  structure  of  bones  and  cartilages,  which  make  up  the 
chief  part  of  the  skeletal  framework,  has  been  already  suf- 
ficiently considered. 

The  ligaments,  which  bind  the  parts  of  the  skeleton  together, 
mostly  consist  of  dense  white  fibrous  tissue,  and  are  character- 
ized by  firm,  unyielding  strength ;  a  few  ligaments,  however, 
the  ligamentum  nuchse  of  animals  and  the  ligamenta  subflava 
of  the  spine,  consist  of  elastic  tissue  and  are  serviceable  by 
virtue  of  their  elasticity. 

Fasciae  are  chiefly  composed  of  interlacing  white  fibrous 
tissue. 

The  articulations  of  the  bones  with  one  another  are  of  three 
kinds — synarthroses,  in  which  the  joint  is  immovable  ;  amphi- 
arthroses,  in  which  there  is  limited  motion ;  and  diarthroses, 
in  which  motion  is  more  or  less  free. 

The  synarthroses,  or  immovable  joints,  are  exemplified  by 
the  bones  of  the  skull  and  face,  immovably  united  or  dove- 
tailed together  by  sutures. 

In  the  amphiarthroses  a  layer  of  fibro-cartilage  is  interposed 
between  the  uniting  bones  (forming  a  "  synchondrosis  "),  the 
articulation  being  reinforced  by  ligaments.  There  is  no  synov- 
ial joint-cavity  and  no  surfaces  moving  on  each  other,  the 
limited  amount  of  motion  possible  being  effected  by  the  flexi- 
bility of  the  cartilaginous  junction.  The  inter  vertebral  junc- 
tions and  the  pubic  and  sacro-iliac  symphyses  are  amphiar- 
throdial  joints. 

The  intervertebral  discs  contain  in  their  centre  a  pulpy 
reticular  mass,  the  remains  of  the  chorda  dorsalis ;  outside 
of  this  is  a  broad  zone  composed  of  lamina?  of  fibro-carti- 
lage, which  merges  at  the  periphery  into  dense  white  fibrous 
tissue. 

The  diarthroses,  or  ordinary  joints,  are  characterized  by  the 


DIARTHROSES.  201 

possession  of  synovial  cavities  and  the  movement  of  the  ends 
of  the  bones  on  one  another. 

The  articular  ends  of  the  bones  entering  into  the  formation 
of  the  joint  are  covered  with  a  layer  of  hyaline  cartilage,  which 
takes  the  place  of  a  periosteum.  The  articular  surface  of  this 
cartilage  is  smooth,  polished,  and  naked,  not  being  covered  by 
perichondrium,  synovial  membrane,  or  endothelium ;  the 
superficial  cartilage-cells  are  flattened,  the  deeper  ones  often 
arranged  in  rows  perpendicular  to  the  surface;  the  deepest 
stratum  of  the  cartilage  is  calcified. 

At  the  margins  of  the  joint  the  articular  cartilages  are  con- 
tinuous with  synovial  membrane,  which  closes  the  sides  of  the 
joint,  and  together  with  the  cartilages  completely  incloses  and 
lines  the  joint-cavity. 

Beneath  the  synovial  membrane  is  areolar  and  fatty  tissue, 
filling  in  the  spaces  between  the  bony  parts. 

The  synovial  membrane  in  places  projects  into  the  cavity  as 
vascular,  fatty,  or  fibrous  ridges,  fringes,  or  villi. 

The  exterior  of  the  joint,  outside  the  subsynovial  tissue,  is 
firmly  bound  together  by  ligaments.  In  some  joints  the  mar- 
gins of  the  articulating  surfaces  are  deepened  by  rims  ofjibro- 
cartilage,  as  in  the  shoulder  (glenoid  ligament),  hip  (cotyloid 
ligament),  and  knee  (semilunar  cartilages). 


CHAPTER    XVI. 

THE  NERVOUS  SYSTEM. 

THE  nervous  system  is  the  seat  and  apparatus  of  sensation, 
consciousness,  coordination,  and  volition,  and  its  elements  are 
distributed  throughout  all  parts  of  the  body.  Nervous  tissues 
are  of  epiblastic  origin  and  constitute  a  class  of  tissues  sui 
generis. 

Division  :  The  nervous  system  can  for  practical  convenience 
be  divided  into  the  nerve-centres,  nerve-trunks,  and  distal 
nerve-terminals ;  and  the  tissue-elements  corresponding  to 
these  respectively  are  nerve-cells,  nerve-fibres,  and  nerve- 
terminals. 

The  cells  and  centres  are  concerned  with  the  distribution 
and  storage  of  nervous  energy;  the  fibres  conduct  nervous  im- 
pulses; and  the  terminals  are  connected  with  the  transfor- 
mation of  nervous  force  into  other  forms  of  energy,  and  vice 
versa. 

According  to  present  prevailing  conceptions,  the  structural 
and  functional  units  of  the  nervous  system  are  elements  called 
neurons,  and  the  subject  is  here  presented  from  this  stand- 
point. A  neuron  is  a  single  nerve-cell  with  all  its  parts  and 
processes.  The  nerve-fibres  are  regarded  as  greatly  elongated 
processes  of  nerve-cells,  so  that  a  neuron  would  include  the 
body  of  the  nerve-cell,  its  nearby  processes,  the  nerve-fibre 
connected  with  it,  perhaps  extending  a  long  distance  to  the 
periphery  of  the  body,  and  the  peripheral  terminations  of  the 
nerve-fibre.  A  neuron  therefore  simply  represents  a  single 
complete  nerve-cell  with  all  its  parts. 

Nerve -cells. 

Nerve-cells  (or  ganglion-cells) :  In  the  full  sense  of  the  term 
"  cell,"  a  nerve-cell  is  the  same  as  a  neuron  ;  but  as  ordinarily 

202 


NERVE-CELLS.  203 

used  the  terra  nerve-cell  is  conveniently  applied  to  the  main 
body  of  these  cells,  regardless  of  the  extended  processes. 
Such  a  term  as  neurosome  would,  perhaps,  be  a  better  desig- 
nation for  the  nerve-cell  body.  Nerve-cells  are  ordinarily  of 
large  size,  and  are  situated  in  the  ganglia  and  cerebro-spinal 
centres.  Their  cytoplasm  usually  consists  of  a  network  of 
fibrils  (spongioplasm),  in  the  meshes  of  which  is  a  more  fluid, 
homogeneous  protoplasm  (hyaloplasm),  sometimes  called 
neuroplasm. 

The  cell-bodies  often  contain  granules  (chromophilic  gran- 
ules) which  stain  deeply  with  various  dyes,  especially  basic 
stains ;  pigment  is  also  sometimes  present.  There  is  no  definite 
cell-envelope. 

Nerve-cells  possess  each  a  large  vesicular  nucleus,  usually 
poor  in  chromatin,  and  hence  not  staining  deeply ;  within  the 
nucleus  is  a  large  nudeolus.  In  shape  nerve-cells  vary,  being 

FIG.  76. 


Body  of  multipolar  nerve-cell  from  spinal  cord  (Nissl's  stain),  showing  details  of 
the  structure  (Ramon  y  Cajal).  a,  neurite;  6,  c,  cytoplasm,  containing  coarse 
chromophilic  granules  ;  d,  nucleus,  with  nucleolus ;  e,  dendrite. 

spherical  (ganglia),  oval,  fusiform,  pyramidal  (cerebrum),  or 
stellate  (spinal  cord). 


204 


THE  NERVOUS  SYSTEM. 


Nerve-cells  are  strongly  characterized  by  the  possession  of 
processes,  often  greatly  prolonged  and  very  complex,  ranging 
in  number  from  one  to  many ;  at  least  one  process  is  always 
present.  The  processes  consist  largely  of  prolongations  of 
the  spongioplastic  fibrils  of  the  cytoplasm. 

Nerve-cells  are  classed  as  unipolar,  bipolar,  and  multipolar 
according  as  they  possess  one,  two,  or  several  processes  re- 
spectively. Another  variety  of  ganglion-cell,  which  may 

FIG.  77. 


Nerve-cells  from  cerebral  cortex  (Ramon  y  Cajal).  A,  small  pyramidal  nerve-cell ; 
B,  large  pyramidal  nerve-cells;  C,  D,  polymorphous  nerve-cells;  G,  neurite;  E 
and  F,  fibres  in  white  matter.  The  arrows  indicate  directions  of  nerve-impulses. 

be  called  pseudo-unipolar,  is  apparently  unipolar,  but  prac- 
tically bipolar;  it  possesses  a  single  process  which  soon 
divides  like  a  T  into  two  processes  ;  embryonically  this  cell  is 
bipolar. 


NEURITES.  205 

The  processes  of  nerve-cells  are  of  two  very  distinct  kinds, 
dendrites  or  protoplasmic  processes,  and  neurites  or  axis- 
cylinder  processes. 

The  dendrites,  or  protoplasmic  processes,  are  long  slender  ex- 
tensions or  processes  from  the  body  of  the  nerve-cells,  usually 
dividing  and  subdividing  into  branches  like  a  tree,  forming 
extensive  "arborizations"  in  the  vicinity  of  the  cell.  As 
they  divide,  the  branches  decrease  in  size  to  fine  terminal 
twigs,  which  have  either  pointed  or  rounded  ends.  The  ter- 
minals of  dendrites  have  been  called  teledendrites.  The  num- 
ber of  dendrites  given  off  by  each  nerve-cell  varies ;  there  may 
be  none  or  several.  The  cerebro-spinal  nerve-cells  possess  the 
most  numerous  and  best  developed  dendrites,  each  having  a 
number  of  such  processes,  while  the  cells  of  the  ganglia  are  less 
abundantly  supplied  with  them,  and  unipolar  cells  lack  them 
altogether.  The  dendrites  of  neighboring  nerve-cells  inter- 
lace and  lie  in  close  relation  with  one  another ;  but  according 
to  the  neuron  theory  they  are  not  actually  united  or  structu- 
rally continuous  together. 

The  neurites,  axis- cylinder  processes,  or  neuraxons,  are 
slender  filamentary  processes  from  nerve-cells,  which  are  pro- 
longed as,  and  become  continuous  with,  the  axis-cylinders  of 
nerve-fibres,  and  as  such  are  greatly  prolonged,  often  extend- 
ing to  the  periphery  of  the  body.  They  acquire  medullated 
envelopes  at  a  short  distance  from  the  cells,  and  thus  become 
converted  into  nerve-fibres.  Sometimes,  within  the  substance 
of  the  nerve-centres,  neurites  give  off  delicate,  short  lateral 
branches,  the  collateral  fibres,  but  aside  from  these  and  except 
at  their  distal  ends  neurites  do  not  branch,  and  their  diameter 
is  uniform  throughout.  All  nerve-cells  possess  one  neurite, 
sometimes  more  than  one ;  if  a  cell  has  but  one  process,  that 
process  is  a  neurite. 

At  their  distal  ends  neurites  or  nerve-fibres  usually  termi- 
nate in  fine  branches;  these  distal  terminations  have  been 
called  teleneurites.  According  to  the  length  of  the  neurites 
and  the  situation  of  the  teleneurites,  two  types  of  nerve-cells 
or  neurons  are  recognized. 

Nerve-cells  of  the  first  type  have  long  neurites  extending 
to  the  visceral,  distal,  or  peripheral  portions  of  the  body, 
where  their  terminals  or  teleneurites  are  situated. 


206  THE  NERVOUS  SYSTEM. 

Those  of  the  second  type  have  a  short  neurite  which  does 
not  emerge  from  the  nerve-centres,  but  not  far  from  its 
origin  divides  into  its  terminal  branches  or  fibrils, — some- 
times forming  a  basket-like  network  enveloping  another 
nerve-cell.  Neurons  of  the  second  type  are  situated  entirely 
within  the  nerve-centres,  those  of  the  first  type  partly  within 
the  nerve-centres,  partly  without,  in  the  general  body-struct- 
ures. 

A  neuron  typically  consists  of  a  nerve-cell  or  cell-body,  one 
or  more  dendrites,  and  a  neurite  prolonged  as  the  axis-cylinder 
of  a  nerve-fibre  to  the  distal  part  of  the  body  (or  to 
another  part  of  the  nerve-centres),  where  it  has  a  special 
termination. 

From  the  nature  of  nervous  action,  as  we  conceive  it,  a 
neuron  must  have  a  mechanism  both  for  receiving  nervous 
impulses  and  for  sending  them  out  again.  Each  neuron  is 
supposed  to  be  complete  in  itself,  and  to  have  no  anatomical 
connection  or  continuity  with  other  neurons ;  the  processes  of 
one  nerve-cell  are  believed  not  to  be  united  to  those  of 
other  cells. 

As  it  is  evident  that  some  communication  of  nervous  impulses 
takes  place  from  one  neuron  to  another,  it  is  supposed  that 
such  communication  occurs  through  contact  of  the  processes 
or  other  parts  of  different  cells  with  one  another.  If  the  cell- 
processes  are  retracted  (as  by  amoeboid  movement)  or  diseased, 
the  communication  may  be  cut  off  and  altered  nervous  condi- 
tions result. 

Another  conceivable  mode  of  transfer  of  nervous  impulses 
from  one  cell  to  another,  possible  without  direct  contact  or 
continuity,  might  be  by  a  sort  of  induction,  analogous  to 
electric  induction. 

Function  of  dendrites  and  neurites  :  It  is  by  some  supposed 
that  the  dendrites  are  afferent  or  centripetal  (cellulipetal)  in 
their  action,  conducting  impulses  to  the  nerve-cell,  and  that 
the  neurites  are  efferent  or  centrifugal  (cellulifugal),  convey- 
ing impulses  from  the  cell  and  degenerating  when  their  con- 
nection with  the  cell  is  severed  ;  this  supposition  is  clear 
enough  with  respect  to  motor  and  other  efferent  nerve-cells 
and  fibres,  but  it  is  not  so  obvious  in  the  case  of  sensory  and 
afferent  fibres, 


AXIS-CYLINDER. 


207 


FIG.  78. 


Nerve-fibres. 

Nerve-fibres  are  regarded  as  processes  of  nerve-cells,  being 
the  continuations  of  neurites,  enveloped 
by  certain  sheaths.  They  connect  nerve- 
cells  with  nerve-terminals,  and  their  func- 
tion is  the  conduction  of  nervous  impulses. 
Nerve-fibres  are  situated  both  within  and 
without  the  cerebro-spinal  centres,  with 
certain  differences  in  their  envelopes  in  the 
two  situations.  In  their  passage  through 
the  body  the  fibres  are  united  by  sustentac- 
ular  tissue  into  bundles,  the  nerves  or  nerve- 
trunks.  Nerve-fibres  are  of  two  kinds, 
medullated  and  non-medullated. 

Medullated  nerve-fibres  (Fig.  78),  also 
called  myelinic  or  white  fibres,  make  up  the 
chief  part  of  the  cerebro-spinal  nerves  and 
occur  also  in  large  numbers  in  the  cerebro- 
spinal  structures.  Where  most  developed 
they  consist  of  three  parts — axis-cylinder, 
medullary  sheath,  and  neurilemma.  Within 
the  cerebro  spinal  centres  there  is  no  neuri- 
lemma, and  at  the  terminations  of  the  fibres 
both  neurilemma  and  medullary  sheath  are 
wanting. 

The  axis-cylinder,  or  axon,  the  prolonga- 
tion of  a  neurite,  is  a  fine  continuous  fila- 
ment, uniform  in  size,  occupying  the  centre 
or  axis  of  the  fibres.  In  medullated  fibres 
the  axis-cylinder  does  not  branch  except  for 
the  "  collateral  fibres,"  and  near  its  distal 
termination,  where  it  may  divide  at  a  node 
of  Ranvier.  It  exhibits  fine  longitudinal 
striations,  apparently  representing  spongio- 
plastic  fibrilla?  bound  together  by  cement  or 
protoplasm.  It  is  the  essential  and  conduct- 
ing portion  of  the  fibres,  the  medullary  sheath  and  neurilemma 
serving  as  coverings  for  it.  [&J.  its  central  end  the  axis- 
cylinder  emerges  as  a  process  from  a  nerve-cell,  and  at  its 


d- 


Segment  of  a  medul- 
lated nerve-fibre,  a, 
node  of  Ranvier; 
6,  neurilemma :  c, 
medullary  sheath  ; 
rf,  axis-cylinder;  e, 
incisure  of  Schmidt; 
/,  nucleus  of  neuri- 
lemma. 


208  THE  NERVOUS  SYSTEM. 

distal  extremity  usually  breaks  up  into  branches  or  fibrils 
connected  with  terminal  structures.  Axis-cylinders  are  of 
epiblastic  origin,  developing  as  outgrowths  from  the  primitive 
nerve-cells. 

The  medullary  sheath,  or  white  substance  of  Schwann,  is 
an  envelope  of  semisolid  material  investing  the  axis-cylinder, 
the  presence  of  which  is  the  main  feature  distinguishing 
medullated  from  non-medullated  nerve-fibres.  It  begins  near 
the  exit  of  the  neurite  from  the  nerve-cell  and  extends  nearly 
to  the  distal  termination  of  the  fibre.  It  protects  and  per- 
haps insulates  the  axis-cylinder.  The  medullary  substance 
consists  of  an  oily,  refraetile,  semifluid  substance  called 
my  din,  supposed  to  be  supported  in  a  reticulum  or  sheath  of 
a  horny  substance  termed  neurokeratin. 

At  regular  intervals  the  nerve-fibres  exhibit  constrictions, 
the  nodes  of  Ranvier,  dividing  the  fibres  into  internodal  seg- 
ments. At  these  nodes  the  continuity  of  the  medullary  sheath 
is  interrupted,  the  neurilemma  and  axis-cylinder  coming 
together  at  these  points.  In  each  internodal  segment  the 
medullary  sheath  exhibits  a  number  of  oblique  or  conical 
markings  or  divisions,  called  the  incisures  of  Schmidt  or  of 
Lantermann;  the  nature  of  these  is  not  definitely  known. 

The  neurilemma,  or  sheath  of  Schwann,  is  a  thin  homo- 
geneous membrane  forming  the  outer  covering  of  the  nerve- 
fibre.  It  is  present  only  in  the  portion  of  the  fibres  included 
in  the  nerve-trunks,  being  absent  in  the  cerebro-spinal  centres, 
where  its  place  is  taken  by  neuroglia.  It  also  disappears 
at  the  nerve-terminations.  At  the  nodes  of  Ranvier  it  comes 
into  contact  with  and  is  cemented  to  the  axis-cylinder,  inter- 
rupting the  continuity  of  the  medullary  sheaths  at  those 
points.  At  the  middle  of  each  internodal  segment  a  nucleus 
surrounded  by  a  small  amount  of  protoplasm  is  situated 
beneath  the  neurilemma.  This  nucleus  apparently  belongs 
to  the  neurilemma,  and  each  nucleated  segment  of  the  neu- 
rilemma is  commonly  regarded  as  a  specialized  single  connec- 
tive-tissue cell. 

Non-medullated  nerve-fibres,  also  called  amyelinic  or  gray 
fibres,  or  fibres  of  Remak  (Fig.  79),  possess  no  medullary 
sheath.  The  sympathetic  nerves  are  made  up  chiefly  of  this 
kind  of  fibres.  They  consist  in  general  of  axis-cylinders 


NEUROGLIA. 


209 


covered  apparently  by  a  neurilemma  which  exhibits  numerous 
nuclei.     The  axis-cylinders  are  similar  to  those  of  medullated 
fibres,  except  that  they  freely  divide 
and    anastomose    with    one    another,  FlG; 79- 

forming  plexuses.  On  their  surface 
at  intervals  rest  nuclei ;  these  prob- 
ably belong  to  a  neurilemma,  which, 
however,  is  so  thin  and  delicate  as  to 
be  difficult  to  distinguish. 

Nerve-centres. 

The  nerve-centres  are  the  cerebrum, 
cerebellum,  and  spinal  cord,  making 
up  the  cerebro-spinal  structures  ;  and 
the  numerous  ganglia  in  different  parts 
of  the  body. 

The  characteristic  elements  making 
up  the  central  nervous  structures  are 
nerve-cells  and  processes,  nerve-fibres, 
and  a  peculiar  sustentacular  tissue 
called  neuroglia. 

The  pia  mater  also  contributes  a 
certain  amount  of  ordinary  connec- 
tive tissue  to  the  sustentacular  frame- 
work. 

Through  differences  in  the  distri- 
bution of  these  elements  two  parts 
are  distinguishable  in  the  substance 
of  the  cerebro-spinal  structures,  gray 
matter  and  white  matter. 

The   gray  matter   consists  of  neu- 
roglia,   nerve-cells,    ramifying    den- 
d rites,  and  scattered  nerve-fibres,  with  and  without  medullary 
sheaths. 

The  white  matter  is  an  almost  solid  mass  of  parallel  medul- 
lated fibres,  supported  by  neuroglia. 

Neuroglia,   the  chief  sustentacular  tissue  of  the  cerebro- 
spinal    structure,  "is  a  sort  of  connective   tissue,  but  is  of 
epiblastic  origin  and  derived  from  epithelial  elements.      It 
14— Hist. 


Non-medullated  nerve-fibres 
(Key  and  Retzius).  n,  nu- 
clei of  neurilemma;  m,  a 
fibre  which  has  a  partial 
medullary  sheath. 


210  THE  NERVOUS  SYSTEM. 

forms   a  framework   supporting   the  nervous   elements.     It 


KIG.  80 


Spider-cell. 
Neuroglia-cells,  Golgi  stain  (Andriezen). 


consists   of  numerous   cells   ("  glia-cells "),    possessing  very 


GRAY  MATTER   OF  THE  CEREBRAL   CORTEX.      211 

many  fine  processes  which  interlace  with  one  another  to 
form  a  network.  Some  glia-cells,  the  "spider-cells,"  have 
long,  fine  unbranched  processes ;  others,  the  "  mossy  cells," 
have  shorter,  thicker,  and  branching  processes  (Figs.  80,  81). 
A  homogeneous  intercellular  cement-substance  is  perhaps  also 
present,  contributing  to  the  sustentacular  framework. 

The  cerebro-spinal  meninges  are  the  dura  mater,  arachnoid, 
and  pia  mater. 

The  dura  mater  is  a  dense  fibrous  membrane  forming  the 
outer  covering  of  the  brain  and  spinal  cord  ;  its  inner  surface 
is  lined  with  endothelium.  Within  the  cranium  it  is  closely 
applied  to  the  cranial  bones,  forming  their  inner  periosteum. 

The  arachnoid  is  a  delicate  connective-tissue  lamina  and 
reticulum.  Externally  it  presents  a  continuous  free  surface 
lined  with  endothelium  ;  this  surface  is  opposed  to  the  dura 
and  separated  from  it  by  a  large  lymph-space,  the  subdural 
space.  The  deeper  portion  of  the  arachnoid  is  a  network  of 
delicate  fibrous  lamina?  and  cords,  lined  on  their  free  surfaces 
with  endothelium  ;  this  network  is  connected  and  continuous 
with  the  pia  mater,  and  the  cavities  enclosed  in  it  form  a 
system  of  communicating  lymph-spaces,  called  the  subarach- 
noid  space. 

The  pia  mater  intimately  invests  and  follows  the  surface  of 
the  brain  and  cord  ;  it  consists  of  delicate  vascular  connective 
tissue,  often  containing  irregular  pigment-cells.  At  intervals 
it  sends  supporting  fibrous  trabecula?  inward  into  the  sub- 
stance of  the  brain  and  cord. 

The  Cerebrum. 

The  cerebrum  consists  of  aggregations  of  white  and  gray 
matter. 

The  ivhite  matter  is  composed  of  radiating  masses  of  medul- 
lated  nerve-fibres,  and  occupies  the  interior  and  central  por- 
tions of  the  organ. 

The  gray  matter,  containing  the  nerve-cells,  covers  the  sur- 
face of  the  cerebrum  and  also  occurs  in  the  central  and  basal 
ganglion ic  tracts. 

The  gray  matter  of  the  cerebral  cortex  in  general  (though 
with  variations  in  some  situations)  exhibits  the  following 


212 


THE  NERVOUS  SYSTEM. 


FIG.  82. 


layers  (Fig.  82),  which  are  not  sharply  marked  off  from  one 
another.  Beneath  the  pia  mater  on  the  surface  is  a  narrow  molec- 
ular zone,  consisting  of  neuroglia,  glia-cells,  terminal  branches 

of  nerve- cell  processes,  and  fine 
medullated  fibres  running  tan- 
gentially  or  parallel  to  the  surface. 
Beneath  this  is  a  zone  character- 
ized by  the  presence  of  small 
pyramidal  nerve-cells.  These  are 
long  pyramidal  cells,  with  their 
apices  directed  toward  the  sur- 
face. Each  cell  gives  off  an  axis- 
cylinder  process  from  its  base, 
running  (for  the  most  part)  into 
the  white  matter  beneath.  From 
the  angles  at  the  apex  and  base 
of  the  cell  are  given  off  dend rites 
which  divide  into  branches  in  the 
vicinity.  This  layer  merges  be- 
low into  a  broad  zone  character- 
ized by  large  pyramidal  nerve- 
cells,  similar  to  those  just  de- 
scribed, but  of  larger  size.  Be- 
neath this  zone  is  a  layer  contain- 
ing polymorphous  nerve-cells  of 
various  shapes — stellate,  irregu- 
lar, and  fusiform.  Neuroglia- 
cells  are  scattered  about  among 
the  nerve-cells  in  the  various 
zones. 

The  foregoing  layers  comprise 
the  cortical  gray  matter.  Be- 
neath them  is  the  white  matter  of  the  interior,  which  at  regu- 
lar intervals  sends  slender,  tapering  bundles  of  medullated 
fibres  radiating  into  the  lower  layers  of  the  gray  matter. 

The  ganglionic  parts  of  the  cerebrum,  as  the  corpus  striatum, 
optic  thalamus,  corpora  quadrigemina,  olfactory  bulb  (or 
nerve),  consist  of  gray  and  white  matter  variously  distributed, 
with  nerve-cells  of  various  forms — multipolar,  stellate,  fusi- 
form, etc. 


Nerve-cells  of  cerebral  cortex  (Ca- 
jal).  1,  molecular  zone ;  2,  small 
pyramidal  nerve-cells  ;  3,  large 
pyramidal  cells ;  4,  polymor- 
phous cells  ;  5,  white  matter. 


GRAY  MATTER   OF  THE  CEREBELLAR   CORTEX.    213 

The  crura  cerebri,  pons,  and  medulla  oblongata  are  composed 
largely  of  white  matter,  or  bundles  of  nerve-fibres  passing 
into  the  cerebrum  and  cerebellum,  intermingled  with  tracts  of 
gray  matter. 

The  ventricles  of  the  brain,  continuous  with  the  central 
canal  of  the  spinal  cord,  are  mostly  lined  with  "  ependyma"  a 
single  layer  of  columnar  epithelium,  ciliated  (especially  in 
youth),  resting  upon  a  neurogliar  basis.  The  columnar  cells 
are  related  to  the  glia-cells. 

In  various  parts  of  the  brain  are  found  corpora  amylacea, 
minute  rounded  granules  with  concentric  markings,  resembling 
starch-granules  in  appearance  and  chemical  reactions. 

The  Cerebellum. 

The  central  portion  of  the  cerebellum  is  a  mass  of  white 
matter,  within  which  is  an  irregular  nodule  of  gray  matter, 
the  dentate  body.  Other  nodules  of  gray  matter  occur  in  the 
upper  part  of  the  organ. 

The  superficial  portion  of  the  cerebellum  is  divided  into 
branching  laminae,  which  in  cross-section  appear  like  the 
branches  of  a  tree,  whence  they  are  called  the  arbor  vitse. 
These  Iamina3  consist  of  a  central  core  or  axis  of  white  matter, 
covered  on  each  side  with  gray  matter. 

The  gray  matter  of  the  cerebellar  cortex  exhibits  two  well- 
marked  layers,  the  nuclear  layer  and  the  molecular  layer, 
between  which  is  a  stratum  formed  by  the  bodies  of  the  cells 
of  Purkinje. 

The  nuclear  or  granule  layer  is  a  broad  zone  lying  next  to 
and  on  each  side  of  the  central  white  matter,  and  contains  a 
crowded  mass  of  small  multipolar  nerve-cells  with  prominent 
deeply  staining  nuclei  and  small  cell-bodies.  Scattered  about 
among  these  cells  are  a  few  larger  multipolar  nerve-cells  and 
glia-cells,  while  mednllated  nerve-fibres  passing  into  the  cen- 
tral white  matter  are  numerous  throughout  the  nuclear  layer. 

The  cells  of  Purkinje,  or  "  antler-cells/'  are  conspicuous 
nerve-cells,  the  bodies  of  which,  separated  by  intervals,  are 
disposed  in  a  single  layer  at  the  junction  of  the  nuclear  and 
molecular  layers.  Their  bodies  are  very  large,  rounded  or 
flask-shaped,  nucleated,  nucleolated,  and  from  their  superficial 


214  THE  NERVOUS  SYSTEM. 

aspect  (that  directed  toward  the  surface)  give  off  coarse  proto- 
plasmic processes  which  divide  and  subdivide  (in  narrow 
transverse  planes)  into  extensive  arborizations  occupying  the 
entire  thickness  of  the  molecular  layer;  from  the  deeper 
aspect  each  cell  gives  off  an  axis  cylinder  process  which  passes 
inward  through  the  nuclear  layer. 

The  mokcular  layer  is  the  superficial  stratum  of  the  cere- 
bellar  cortex,  and  consists  chiefly,  besides  neuroglia,  of  the 
extensive  interlacing  ramifications  of  the  dendrites  of  the  cells 
of  Purkinje  and  of  the  processes  of  other  nerve-cells  in  the 
vicinity.  This  layer  also  contains  scattered  small  multi polar 
nerve-cells  ;  the  neurites  of  some  of  these  cells  ("  basket  cells") 
run  parallel  to  the  surface  and  give  off  branches  which  break 
up  into  terminal  basket-like  networks  of  fibrils  that  surround 
the  bodies  of  Purkinje's  cells. 

The  Spinal  Cord. 

The  spinal  cord  is  divided  into  symmetrical  lateral  halves  by 
the  deep  and  narrow  posterior  median  "  fissure "  (really  a 
fibrous  septum)  and  the  broad  but  shallower  anterior  median 
fissure. 

The  periphery  of  the  cord  is  formed  by  white  matter,  con- 
sisting of  a  dense  mass  of  longitudinal  medullated  nerve- 
fibres,  supported  by  neuroglia  and  narrow  connective-tissue 
extensions  from  the  pia  mater  passing  radially  inward.  The 
narrow  layer  of  white  matter  intervening  between  the  gray 
commissure  and  the  fundus  of  the  anterior  median  fissure  con- 
stitutes the  "anterior"  or  "white  commissure." 

From  physiological  and  pathological  considerations  the 
white  fibres  of  the  cord  are  divisible  into  definite  longitudinal 
tracts,  but  these  divisions  are  only  partially  apparent  to  sight 
in  the  normal  cord  (Fig.  84). 

The  interior  of  the  cord  is  occupied  by  gray  matter,  which 
consists  of  two  lateral  parts,  curved  outward,  joined  by  a 
transverse  portion  (the  "gray  commissure"),  thus  in  cross- 
section  roughly  exhibiting  an  H  shape. 

The  gray  matter  is  composed  of  neuroglia,  interlacing  den- 
drites, nerve-fibres  (with  and  without  medullary  sheaths),  and 
nerve-cells. 


NERVE-CELLS. 


215 


The  portions  of  the  gray  matter  which  approach  the  surface 
of  the  cord  anteriorly  and  posteriorly  are  called  the  anterior 
(or  ventral)  and  posterior  (or  dorsal)  horns  or  cornua ;  the 
anterior  horns  are  broader  and  shorter ;  the  posterior  longer 
and  narrower. 

From  these  horns  at  intervals  proceed  the  posterior  (sensory) 
and  anterior  (motor)  roots  of  the  spinal  nerves. 


Cross-section  of  the  spinal  cord  of  a  newborn  child,  showing  the  distribution  within 
the  gray  matter  of  the  collaterals  from  the  neurites  of  the  white  matter  (R.  y 
Cajal ).  a,  anterior  fissure ;  B,  pericellular  branches  of  the  collaterals  from  the 
anterior  column  ;  C,  collaterals  of  the  anterior  commissure  ;  D,  posterior  bundle 
of  collaterals  in  the  posterior  commissure ;  E,  middle  bundle  of  the  posterior 
commissure  ;  /,  anterior  bundle ;  G,  collaterals  from  the  posterior  column ;  H, 
senso-motory  collaterals  from  the  posterior  column  ;  I,  pericellular  terminations 
of  collateral's  in  the  posterior  horn ;  J,  collateral  terminations  in  the  column  of 
Clarke. 

The  nerve-cells  of  the  cord  (Fig.  76)  are  arranged  in  definite 
longitudinal  series  or  columns,  as  follows :  (a)  in  the  anterior 
horn  are  numerous  very  large  stellate  multipolar  motor  cells ; 


216 


THE  NERVOUS  SYSTEM. 


in  the  posterior  horn  are  smaller  and  less  numerous  nerve- 
cells  ;  (c)  the  vesicular  column  of  Clarke  is  a  column  of  medium- 
sized  nerve-cells,  not  continuous  along  the  entire  cord,  on  the 
inner  sides  of  the  posterior  cornua  ;  (d)  the  intermedio-lateral 
column  is  a  series  of  small  nerve-cells  laterally  situated  (in  the 
"  lateral  horn  ")  in  the  dorsal  portion  of  the  cord. 

FIG.  84. 


Cross-section  of  human  spinal  cord,  middle  dorsal  region  (Rchafer).  a,  5  c,  nerve- 
cells  of  anterior  horn  ;  d,  intermedio-lateral  column  of  nerve-cells  ;  /,  nerve- 
cells  of  Clarke's  column ;  g,  nerve-cells  of  posterior  horn ;  cc,  central  canal ;  ac, 
anterior  white  commissure. 

The  central  canal  is  a  small  tube  in  the  middle  of  the  gray 
commissure  extending  the  whole  length  of  the  cord  and  con- 
tinuous with  the  ventricles  of  the  brain ;  it  is  lined  with  a 
single  layer  of  columnar  epithelium-cells,  ciliated  in  youth, 
surrounded  by  neuroglia. 

The  neuroglia  capping  the  posterior  horns  and  surrounding 
the  central  canal — the  "  substantia  gelatinosa  " — is  somewhat 
homogeneous  and  glistening. 

Ganglia. 

Ganglia  are  small  macroscopic  to  microscopic  aggregations 
of  nerve  cells  and  fibres,  occurring  abundantly  in  various 
parts  of  the  body.  Since  they  contain  nerve-cells,  their 


ARRANGEMENT  OF  NERVES.  217 

nature  and  function  are  essentially  those  of  nervous  centres. 
Some  of  them  belong  to  the  cerebro-spinal  system  of  nerves 
— e.  f/.j  most  of  the  ganglia  connected  with  the  cerebral  nerves 
and  those  on  the  posterior  roots  of  the  spinal  nerves ;  others 
pertain  to  the  sympathetic  system,  as  the  lateral  and  anterior 
spinal  and  the  visceral  ganglia. 

Typical  ganglia  are  enveloped  in  a  fibrous  capsule  continu- 
ous with  the  epineurium  of  the  tributary  nerves.  The  nerve- 
ceils  in  the  ganglia  are  aggregated  in  elongated  or  rounded 
clusters,  separated  by  bundles  of  (rnedullated  or  non-medul- 
lated)  nerve-fibres.  Each  nerve-cell  is  surrounded  by  a 
membranous  nucleated  capsule,  composed  of  connective-tissue 
cells,  continuous  with  the  neurilemma  of  the  issuing  nerve- 
fibre. 

The  ganglia  of  the  posterior  roots  of  the  spinal  nerves  con- 
sist of  medullated  fibres  and  large  globular  encapsulated 
nerve-cells,  nucleated  and  nucleolated.  In  man  these  nerve- 
cells  when  mature  possess  a  single  process  which  at  a  short 
distance  from  the  cell  divides  like  a  T  into  two  branches 
going  in  contrary  directions  ;  these  cells  are  practically  bipolar, 
as  they  actually  are  morphologically  in  some  animals  and 
the  human  embryo. 

The  sympathetic  ganglia  similarly  consist  of  nerve-fibres 
(non-medullated  and  medullated)  and  nerve-cells.  The  latter 
are  encapsulated,  multipolar,  often  pigmented,  occasionally  in 
man  (regularly  in  some  animals)  possessing  two  nuclei.  Many 
of  the  sympathetic  ganglia  are  very  minute,  imbedded  in  the 
substance  of  the  viscera,  as  the  heart  and  the  intestines. 

The  Nerves. 

The  nerves,  or  nerve-trunks,  consist  of  bundles  of  nerve-fibres 
bound  together  by  sustentacular  connective  tissue. 

The  cerebro-spinal  nerves  consist  mainly  of  medullated 
fibres ;  the  sympathetic  nerves  chiefly  of  non-medullated  fibres. 

The  arrangement  of  nerves  (especially  the  cerebro-spinal) 
corresponds  to  that  of  voluntary  muscle.  The  individual 
fibres  are  grouped  in  bundles  or  "  funiculi "  ;  and  these  again 
into  the  entire  nerve-trunks  (except  in  small  nerves  consisting 
of  single  funiculi).  The  entire  nerve  is  enveloped  in  a  con- 


218  THE  NERVOUS  SYSTEM. 

nective-tissue  sheath,  called  the  epineurium.  The  separate 
funiculi  are  surrounded  by  similar  fibrous  sheaths,  the 
perineuriwn,  continuous  with  the  epineurium.  Within  the 
funiculi  is  a  delicate  connective  tissue,  the  endoneurium,  pene- 
trating among  the  individual  nerve-fibres. 

The  larger  blood  and  lymphatic  vessels  are  situated  in  the 
perineurium  and  send  capillaries  into  the  endoneurium.  In 
the  small  terminal  nerves  the  epineurial  covering  consists  of 
a  layer  of  flattened  connective-tissue  or  endothelioid  cells, 
called  the  "  sheath  of  Henle." 

Nerve-terminals. 

The  axis-cylinders  of  nerve-fibres  at  their  distal  terminations 
lose  their  coverings  and  divide  into  fine  terminal  fibrils,  or 
"  teleneurites."  Some  of  these  terminals  are  situated  in  the 
gray  matter  of  the  nerve-centres,  and  are  distributed  in  a 
manner  analogous  to  the  dendrites ;  others  are  distributed 
throughout  the  tissues  of  the  body  (somatic  terminals),  and 
are  often  associated  with  special  structures  exhibiting  great 
diversity  and  specialization  of  function  and  form  ;  some  of 
them  being  highly  developed  and  complex  organs,  such  as  the 
eye  and  ear. 

From  a  functional  standpoint  these  somatic  terminals  can 
be  divided  into  two  classes,  afferent  and  efferent. 

The  afferent  nerve-terminals  have  sensory  functions  and 
initiate  nerve-impulses  which  travel  along  the  fibres  to  the 
nerve-cells. 

The  efferent  terminals  receive  impulses  (motor,  secretory, 
trophic,  etc.)  from  the  nerve-cells  and  impart  them  to  the 
organs  with  which  they  are  associated. 

In  general,  the  function  of  the  somatic  terminals  is  con- 
nected with  the  transformation  of  other  forms  of  energy  into 
the  particular  mode  of  molecular  energy  which  constitutes 
nervous  force  ;  and  with  the  retransformation  of  the  latter  into 
ordinary  modes  of  motion. 

Classes  of  nerve-terminals:  Only  the  nerve-endings  found 
in  man  are  here  considered  ;  other  terminals  of  similar  gen- 
eral type  occur  in  other  animals. 

The  first  division  of  teleneurites  is  into  those  situated  in 


TERMINAL   FIBRILS.  219 

the  nerve-centres  (which  do  not  here  require  further  consider- 
ation), and  those  situated  outside  the  nerve-centres  (somatic). 
The  somatic  nerve-terminals  of  man  may  be  classified  thus : 

Efferent: 

Terminal  fibrils ; 

Motor  end-plates  of  voluntary  muscle. 


Afferent  : 

Terminal  fibrils ; 

Tactile  cells; 

Tactile  corpuscles  of  Wagner  (or  Meissner) ; 


-  Touch,  etc. 


End-bulbs  of  Krause ; 

Corpuscles  of  Pacini  (or  Vater) ; 

Taste-terminals ; 

Olfactory  terminals; 

Eye; 

Ear. 

Terminal  fibrils  constitute  the  simplest  form  of  nerve-end- 
ings, and  are  widely  distributed,  penetrating  among  the  cells 
of  the  tissues  involved  (Fig.  85).  They  are  continuations  of 
the  axis-cylinders  of  the  nerve-fibres,  which  lose  their  cover- 
ings and  break  up  into  fine  naked  terminal  fibrils.  They 
often  exhibit  bulbous  enlargements  at  intervals,  and  end  in 
bulbs  or  points.  They  divide  and  branch,  and  in  some  places 
anastomose  to  form  plexuses.  They  are  either  efferent  or  af- 
ferent. 

The  chief  examples  of  efferent  fibrillar  nerve-endings  are 
found  in  involuntary  muscle,  the  heart,  and  secretory  glands. 

Non-striated  muscle  (as  in  the  intestine  and  arteries)  is  usu- 
ally associated  with  plexuses  (sometimes  gangliated)  of  non- 
medullated  fibres,  delicate  fibrils  from  which  innervate  the 
muscle-cells. 

The  heart-muscle  is  similarly  innervated. 

In  many  glands,  as  the  salivary,  delicate  plexuses  surround 
the  acini  and  probably  send  fibrils  (apparently  efferent  and 
stimulant  to  secretion)  among  the  individual  epithelium-cells. 

Afferent  (sensory)  terminal  fibrils  occur  in  the  epidermis, 


220 


THE  NERVOUS  SYSTEM. 


mucous  membranes,  voluntary  muscle,  and  doubtless  in  many 
other  situations. 

In  the  epidermis  fibrils  enter  from  the  corium  and  are  dis- 
tributed among  the  cells  of  the  Malpighian  layer.  Similar 
endings  have  been  found  in  the  epithelium  of  the  mucous  mem- 


FIG. 


Terminal  nerve-fibrils  in  epithelium  of  mucous  membrane  (bladder   of  rabbit) 

(Retzius). 

brane  of  the  mouth,  and  occur  in  mucous  membranes  else- 
where. 

The  cornea  contains  delicate  terminal  plexuses  sending 
fibrils  into  the  overlying  conjunctival  epithelium. 

In  voluntary  muscles  fine  terminal  nerve-fibrils  of  sensory 
nature  have  been  demonstrated. 

Motor  end-plates  of  voluntary  muscle  (Fig.  86) :  The  motor 
innervation  of  striated  muscle  is  derived  through  "  end-plates," 
which  are  terminals  of  medullated  nerve-fibres. 

The  end-plate,  of  which  each  muscle-cell  possesses  one,  ex- 
ceptionally more,  is  closely  attached  to  the  surface  of  the 


TACTILE  CORPUSCLES  OF  WAGNER.  221 

muscle-fibre,  in  intimate  relation  with  the  muscle-protoplasm  ; 
whether  it  lies  underneath  or  external  to  the  sarcolemma  is 
unsettled.  The  end-plates  are  flattened  and  elliptical  in  form, 
and  are  made  up  of  terminal  branches  of  the  axis-cylinder 
supported  by  a  protoplasmic  plate  or  "  sole."  The  sole  is  a 
mass  of  granular  protoplasm  containing  a  number  of  nuclei, 
and  forms  a  bed  or  basis  for  the  terminal  nerve-branches. 

The  nerve-fibre  concerned,  on  reaching  the  end-plate,  loses 
its  medullary  sheath,  and  its  axis-cylinder  divides  into  branches, 
enlarged  and  club-shaped,  which  ramify  in  an  arborescent 
way  over  the  end-plate,  supported  on  or  imbedded  in  the  sole. 

FIG.  86. 


End-plate  of  striated  muscle-fibre  of  a  squirrel's  tail  (Galeotti  and  Levi). 

Tactile  cells  occur  scattered  about  in  the  lower  part  of  the 
Malpighian  layer  of  the  epidermis,  and  have  a  tactile  function. 
Each  of  them  consists  of  an  oval  nucleated  cell  with  its  lower 
surface  resting  in  a  meniscus,  a  concavo-convex  or  saucer-shaped 
expansion  of  the  end  of  a  terminal  nerve-fibril.  Terminals  of 
this  type  are  sometimes  called  "  simple  tar-tile  cells,"  in  con- 
tradistinction to  "  compound  tactile  cells "  (corpuscles  of 
Merkel  and  of  Grandry),  not  found  in  man,  in  which  two 
or  more  cells  are  together  associated  with  terminal  nerve- 
plates. 

The  cells  of  Langerham,  stellate  cells  occasionally  found  in 
the  epidermis,  are  by  some  regarded  as  nerve-terminal  cells, 
by  others  as  wandering  leukocytes. 

Tactile  corpuscles  of  Wagner  (or  Mdssner]  :  These  are  ellipti- 
cal structures  situated  in  some  of  the  papillae  of  the  corium  of 


222 


THE  NERVOUS  SYSTEM. 


the  skin  (Fig.  87).  They  are  associated  with  the  sense  of 
touch,  and  are  most  numerous  in  the  hands  and  feet,  where 
the  tactile  sense  is  delicate.  The  details  of  their  structure  are 
obscure.  They  are  elongated,  elliptical  bodies,  lying  in  the 
axis  of  the  papillae,  and  exhibit  transverse  or  spiral  markings. 
At  their  lower  extremity  they  are  joined  by  a  medullated  nerve- 
fibre  (or  sometimes  more  than  one),  the  axis-cylinder  of  which, 
losing  its  coverings,  enters  the  corpuscle,  within  which  it  winds 


FIG. 


FIG.  87. 


Tactile  corpuscle  of  Wagner,  from 
human  corium  (Bohm  and 
Davidoff). 


End-bulb  of  Krause,  from  human 
conjunctiva  (Dogiel). 


about  and  sends  off  lateral  branches.  Some  authorities  regard 
these  corpuscles  as  aggregations  of  transverse  flat  tactile  cells, 
others  consider  them  connective-tissue  structures  with  trans- 
verse septa. 

End-bulbs  or  tactile  corpuscles  of  Krause  (Fig.  88) :  These 
are  small  spherical  structures  in  which  medullated  fibres  ter- 
minate, and  pertain  to  the  sense  of  touch.  They  occur  in  the 
conjunctiva  and  adjacent  portion  of  the  cornea,  in  the  corium 


CORPUSCLES  OF  PACINI. 


223 


of  the  glans  penis  and  clitoris  (genital  corpuscles),  in  the 
vicinity  of  joints  (articular  corpuscles),  and  have  been  found 
in  mucous  membranes  in  other  situations,  as  the  lips,  mouth, 
colon.  They  are  enveloped  in  a  delicate  fibrous  capsule  con- 
taining nucleated  endothelioid  cells.  Within  the  capsule  is  a 
core,  of  uncertain  nature,  in  which  the  axis-cylinder  of  the 
tributary  nerve  fibre  forms  an  intricate  convolution  or  divides 
into  branches. 

Corpuscles  of  Pacini  (or  Voter)  (Fig.  89)  :  These  are  oval  or 

FIG.  89. 


Pacinian  corpuscle  from  mesentery  of  cat  (Klein). 

ellipsoidal  structures,  of  tactile  functions,  two  or  three  milli- 
metres long  and  half  as  broad.  They  occur  in  the  subcuta- 
neous tissue  (especially  of  the  palms  and  soles),  joints,  peri- 
osteum, peritoneum,  mesentery  (especially  near  the  solar 
plexus),  and  other  situations;  they  are  located  especially 
along  the  course  of  nerves.  They  consist  of  the  terminal  axis- 
cylinder,  surrounded  by  a  cylindrical  core,  and  this  again 
enveloped  in  a  series  of  numerous  concentric  lamellae  or  cap- 
sules containing  lymph.  The  axis-cylinder  pursues  a  straight 
course,  lying  in  the  long  axis  of  the  corpuscle ;  sometimes  it 


224  THE  NERVOUS  SYSTEM. 

forks,  or  at  its  distal  extremity  may  end  in  a  bulb  or  divide 
into  fibrils.  The  axis-cylinder  is  surrounded  by  a  granular 
or  perhaps  multinucleated  substance,  which  forms  a  cylindri- 
cal core  or  "  inner  bulb." 

The  bulk  of  the  Pacinian  corpuscle  is  chiefly  made  up  of  a 
series  of  twenty-five  to  fifty  concentric  lamellce,  which  envelop 
the  core.  Each  lamella  consists  of  a  delicate  connective- 
tissue  membrane  lined  by  endothelioid  cells,  the  nuclei  of 
which  appear  prominently  in  sections.  The  lamellae  are  de- 
rived, partly  at  least,  from  the  perineurial  sheaths  of  the 
entering  nerve-fibre,  and  they  are  separated  by  lymph-spaces 
filled  with  serum. 

Taste-terminals :  The  taste-terminals  are  associated  with 
specialized  neuro-epithelial  structures  in  the  tongue,  the  "taste- 
buds"  which  are  described  at  page  119.  The  nerves  of  taste 
end  in  terminal  fibrils  which  are  distributed  through  the  epithe- 
lial lining  of  the  mucous  membrane  in  the  vicinity  of  the  taste- 
buds  ;  some  of  the  fibrils  (intragemmal)  ramify  through  the 
taste-buds ;  others  (intergemmal)  are  distributed  between  them. 

Olfactory  terminals :  The  olfactory  nerve-terminals  consist 
of  fine  terminal  fibrils  distributed  in  the  mucous  membrane 
lining  the  upper  part  of  the  nasal  fossa?,  in  association  with 
specialized  neuro-epithelial  or  neural  elements,  the  "  olfactory 
cells,"  which  are  described  on  page  142. 

The  Eye. 

The  eye  (Fig.  90)  is  a  highly  specialized  camera-like  organ 
associated  with  the  termination  of  the  optic  nerve.  Its  parts 
are :  the  conjunctiva,  the  sclerotic  coat  and  cornea  (tunica 
externa),  the  choroid  coat,  ciliary  body  and  iris  (tunica  media 
or  uveal  tract),  the  aqueous  humor,  the  crystalline  lens  and  sus- 
pensory ligament,  the  vitreous  body,  the  retina  (tunica  interna), 
optic  nerve,  and  certain  subsidiary  structures. 

The  conjunctiva  is  a  mucous  membrane  covering  the  front 
of  the  eye  and  inner  surface  of  the  eyelids.  It  consists  of  a 
tunica  propria  covered  with  stratified  columnar  epithelium, 
except  that  over  and  near  the  cornea  the  epithelium  is  of  the 
stratified  squamous  variety  and  over  the  cornea  there  is  no 
tunica  propria. 


THE  SCLEROTIC. 


225 


The  sclerotic  is  the  outermost  tunic  of  the  eye.  Its  anterior 
portion  is  modified  to  form  the  cornea.  It  is  a  thick,  dense 
capsule,  made  up  of  lamina?  of  white  fibres,  between  which  are 


Iris 


FIG.  90. 

Cornea 

Anterior  Chamber 


Posterior  Chamber 
Ciliary  Body 
Ciliary  Processes 


Canal  of. 
Petit 


Canal  of 
Schlemm 


BY       VITREOUS        HUMOUR 


Nerve  sheath 


Nerve 


Canal  for  central 
Artery 

Horizontal  section  through  eye  (Allen). 

flattened  stellate  connective-tissue  cells  and  a  few  elastic 
fibres.  Its  vascular  supply  is  scanty,  but  the  communicating 
pericellular  spaces  form  a  network  of  lymph-passages. 

15— Hist. 


226  THE  NERVOUS  SYSTEM. 

Between  the  sclerotic  and  choroid  coats  is  a  layer  of  loose 
fibro-elastic  tissue  containing  irregular  pigmented  connective- 
tissue  cells ;  the  portion  of  this  tissue  applied  to  the  sclerotic 
is  called  the  lamina  fusca,  that  next  to  the  choroid  the  lamina 
suprachoroidea ;  in  the  midst  of  this  tissue  are  ample  lymph- 
spaces  (subscleral  or  perichoroidal)  lined  with  endothelium. 
Externally  the  sclerotic  rests  in  a  sort  of  synovial  sac,  the 
capsule  of  Tenon. 

The  cornea  is  the  modified  transparent  anterior  portion  of 
the  sclerotic.  It  consists  of  five  layers,  which  are,  from  before 
backward :  epithelium,  anterior  elastic  membrane,  corneal 
substance  proper,  posterior  elastic  membrane,  and  posterior 
endothelium. 

The  epithelial  layer  covering  the  cornea  anteriorly  consists 
of  a  few  layers  of  stratified  squamous  epithelium,  and  is  the 
corneal  portion  of  the  conjunctiva;  the  lowermost  cells  are 
columnar. 

The  anterior  elastic  lamina  (or  "  membrane  of  Bowman")  is 
a  thin,  hyaline,  apparently  homogeneous  layer,  forming  a 
basement-membrane  for  the  epithelium. 

The  substantia  cornece  propria  makes  up  the  main  part  of 
the  cornea,  and  consists  of  transparent  lamina?  of  white  fibres 
bound  together  by  cement-substance.  Between  the  lamina? 
are  numerous  stellate  connective-tissue  cells  with  anastomosing 
branches.  These  cells  and  their  processes  lie  in  spaces  form- 
ing a  network  of  passages  through  which  lymph  can  perco- 
late for  the  nutrition  of  the  cornea,  which  possesses  no  blood- 
vessels. 

Behind  the  substantia  propria  is  the  posterior  elastic  lamina 
(or  "  membrane  of  Descemet "),  a  thin,  homogeneous,  hyaline 
layer  like  the  anterior  one.  Upon  the  free  posterior  surface 
of  this  membrane  is  a  single  layer  of  endothelium-cells,  con- 
tinuous with  those  lining  the  anterior  surface  of  the  iris. 

The  cornea  contains  plexuses  and  terminals  of  nerve-fibrils. 
At  the  junction  of  the  cornea  and  sclerotic,  in  the  substantia 
propria,  is  a  venous  or  lymph-passage,  the  canal  of  Schlemm, 
encircling  the  cornea. 

The  choroid  is  the  thin,  middle  vascular  tunic  of  the  eye. 
Anteriorly  it  is  continuous  with  the  ciliary  body  and  iris. 
The  outermost  layer  of  the  choroid  is  the  lamina  supra- 


THE  CHOROID. 


227 


choroidea,  similar  to  the  lamina  fusca  of  the  sclerotic,  from 
which  it  is  separated  by  lymph-spaces.  Next  to  this  layer  is 
the  main  stroma  of  the  choroid,  or  vascular  layer,  which  con- 
sists of  an  abundance  of  lymphatics  and  large  bloodvessels 
imbedded  in  fibro-elastic  tissue  containing  numerous  pig- 
mented  stellate  connective -tissue  cells. 

FIG.  91. 


Section  through  ciliary  body  and  tunics  of  eye  at  corneo-sclerotic  junction  (Wal- 
deyer).  A,  epithelium  of  conjunctiva ;  B,  tunica  propria  of  conjunctiva;  C, 
sclerotic;  A  laminae  fusca  and  suprachoroidea ;  E,  F,  choroid  ;  G,  pars  retinae 
ciliaris  and  iridica;  H,  cornea;  /,  iris :  K.  M,  radial  and  meridional  portions 
of  ciliary  muscle  ;  L,  circular  portion  of  ciliary  muscle ;  N,  ligamentum  pectina- 
tum;  0.  margin  of  anterior  chamber;  1,  anterior  elastic  lamina  of  cornea;  2, 
posterior  elastic  lamina  and  endothelial  layer  of  cornea :  3,  spaces  of  Fontana ; 
4,  canal  of  Schlemm  ;  5,  6,  vessels  tributary  to  canal  of  Schlemm  ;  7,  8,  9,  fibrous 
bundles  of  sclerotic  cut  transversely;  10,  origin  of  meridional  ciliary  muscle ; 
11, 12,  bloodvessels. 

Next  within  this  is  the  thin  choriooapillary  layer,  a  dense 
capillary  network.  Next  to  this  is  a  thin,  hyaline  homo- 
geneous vitreous  layer  (lamina  basalis,  membrane  of  Bruch), 
the  innermost  layer  of  the  choroid  and  separating  it  from  the 
retina. 


228  THE  NERVOUS  SYSTEM. 

The  ciliary  body  is  a  thickening  of  the  choroid  anteriorly, 
at  its  junction  with  the  cornea,  sclerotic,  and  iris.  Its  sub- 
stance is  similar  to  that  of  the  choroidal  stroma,  consisting  of 
vessels  imbedded  in  connective  tissue ;  the  choriocapillary 
layer  is  wanting,  the  capillaries  being  more  generally  dis- 
tributed. 

Its  posterior  surface  is  thrown  up  into  radiating  processes, 
the  ciliary  processes,  increasing  in  height  toward  the  iris,  at 
the  periphery  of  which  they  abruptly  terminate.  The  vitreous 
membrane  is  continued  over  the  surface  of  these  processes. 

Upon  the  posterior  or  inner  surface  of  this  membrane  rests 
a  layer  of  pigmented  epithelium,  and  then  a  single  layer  of 
columnar  epithelium ;  these  two  layers  are  an  anterior  con- 
tinuation of  the  retina  (pars  ciliaris  retince). 

In  the  substance  of  the  ciliary  body  is  the  ciliary  muscle, 
fasciculi  of  involuntary  muscle  arising  near  the  corneo- 
sclerotic  junction  and  extending  thence  radially  or  meridion- 
ally  outward  and  backward,  together  with  some  circular 
fasciculi. 

The  ciliary  body  at  the  margin  of  the  iris  is  united  to  the 
corneo-sclerotic  junction  by  fibrous  processes,  the  ligamentum 
pectinatum,  the  interstices  of  which  form  the  lymph-spaces  of 
Fontana. 

The  iris  is  attached  by  its  peripheral  margin  to  the  ciliary 
body  at  the  corneo-sclerotic  junction.  It  consists  of  six  layers : 
from  before  backward,  endothelium,  anterior  boundary  layer, 
stroma,  posterior  boundary  layer,  pigment-layer,  and  limit- 
ing membrane. 

The  endothelium  covering  the  anterior  surface  of  the  iris  is 
continuous  with  that  on  the  posterior  surface  of  the  cornea. 

The  anterior  and  posterior  boundary  layers  and  stroma  of 
the  iris  are  continuations  of  choroidal  tissue. 

The  anterior  boundary  layer  is  a  loose  connective  tissue 
containing  lymphoid  cells ;  it  merges  into  the  stroma. 

The  stroma,  or  main  portion  of  the  iris  consists  chiefly  of 
radiating  bloodvessels  and  circular  and  radiating  fasciculi  of 
involuntary  muscle  imbedded  in  connective  tissue.  The  con- 
nective-tissue cells  of  the  stroma  and  anterior  boundary  layer 
contain  pigment  in  varying  amount,  to  which  the  color  of 
the  iris  is  partly  due. 


THE  SUSPENSORY  LIGAMENT.  229 

The  posterior  boundary  layer  is  a  thin  hyaline  layer  corre- 
sponding to  the  vitreous  layer  of  the  choroid. 

The  pigment-layer  is  a  continuation  of  the  retina  (pars 
iridica  retinae),  and  consists  of  densely  pigmented  epithelium- 
cells,  fusiform  anteriorly,  polygonal  posteriorly. 

The  membrana  lirnitans  iridis  is  a  delicate  cuticular  mem- 
brane covering  the  pigment-layer  posteriorly. 

The  aqueous  humor  consists  of  lymph,  containing  a  few 
leukocytes  ;  it  occupies  the  anterior  chamber  of  the  eye,  which 
is  essentially  a  large  lymph-space  communicating  with  the 
ocular  lymphatics  and  is  lined  with  endothelium,  the  same 
layer  which  covers  the  posterior  surface  of  the  cornea  and 
anterior  surface  of  the  iris. 

The  crystalline  lens  consists  of  a  mass  of  epithelioid  lens- 
fibres  covered  by  a  layer  of  epithelium  anteriorly ;  the  whole 
enveloped  in  a  capsule. 

The  anterior  epithelium  is  a  single  layer  of  low  columnar 
cells  covering  the  anterior  surface  of  the  lens  beneath  the 
capsule. 

The  lens-fibres,  composing  the  bulk  of  the  lens,  are  long 
curved  hexagonal  fibres  cemented  together,  arranged  some- 
what concentrically  and  meridionally.  Oval  nuclei  are  pres- 
ent near  the  middle  of  the  fibres  at  the  equator  of  the  lens, 
and  in  all  the  fibres  when  young.  The  lens-fibres  are  greatly 
elongated  epithelium-cells,  derived  from  the  posterior  epithe- 
lium of  the  embryonic  lens.  At  the  equator  of  the  lens  a 
transition  from  the  anterior  epithelium  into  the  posterior 
epithelial  fibres  is  observable. 

The  capsule  is  an  elastic  cuticular  membrane  enveloping 
the  lens. 

The  suspensory  ligament  (zone  of  Zinn,  zonula  ciliaris)  en- 
circles and  supports  the  lens,  being  attached  to  the  capsule  of 
the  latter  near  the  equator.  It  is  a  fibrous  structure,  radially 
plicated  ;  it  is  connected  posteriorly  with  the  hyaloid  mem- 
brane of  the  vitreous  body,  and  with  the  ciliary  body  and 
processes,  so  that  contraction  of  the  ciliary  muscle  relaxes  it 
and  permits  the  elastic  lens  to  increase  in  convexity  and  re- 
fractive powrer.  At  its  union  with  the  lens  it  splits  into  two 
layers,  anterior  and  posterior,  with  a  lymph -space  between 
thenx,  called  the  canal  of  Petit. 


230  THE  NERVOUS  SYSTEM. 

The  vitreous  body  fills  the  large  cavity  of  the  eye.  It  con- 
sists of  a  soft  gelatinous  substance,  scattered  about  in  which 
are  stellate  connective-tissue  cells  and  scanty  fibrous  elements 
— a  sort  of  mucous  tissue.  It  is  surrounded  by  a  homogene- 
ous membrane,  the  hyaloid  membrane,  which  separates  it  from 
the  retina  and  lens. 

The  retina,  the  inner  tunic  of  the  eye,  lies  between  the 
choroid  and  the  vitreous.  It  is  divisible  into  three  parts,  the 
optical,  ciliary,  and  iridic  portions ;  the  two  latter  being  rudi- 
mentary anterior  portions. 

The  pars  retince  iridica  covers  the  posterior  surface  of  the 
iris,  and  consists  of  densely  pigmented  epithelium-cells  covered 
by  a  limiting  membrane. 

The  pars  retince  ciliaris  covers  the  posterior  surface  of  the 
ciliary  body  and  processes,  and  consists  of  layers  of  pigmented 
and  columnar  epithelium  and  an  internal  limiting  membrane. 

A  short  distance  behind  the  ciliary  body  the  pars  retince 
optica  or  main  functional  portion  of  the  retina,  the  retina 
proper,  begins  by  an  abrupt  thickening  or  fold,  the  ora  serrata. 

The  retina  proper  exhibits  the  following  layers,  from  within 
outward  (Fig.  92) :  internal  limiting  membrane  ;  nerve-fibre 
layer  ;  ganglion-cell  layer ;  inner  reticular  layer  ;  inner  nuclear 
layer ;  outer  reticular  layer ;  outer  nuclear  layer ;  external 
limiting  membrane ;  layer  of  rods  and  cones,  and  pigment- 
layer. 

The  elements  making  up  the  retina  are  nervous,  neuro- 
epithelium,  pigmented  epithelium,  and  sustentacular. 

Conspicuous  among  the  sustentacular  elements  are  the 
radiating  fibres  of  MiQler,  specialized  neuroglia-cells.  Their 
inner  ends  are  expanded  and  by  their  junction  form  the  so- 
called  internal  limiting  membrane  of  this  portion  of  the  retina  ; 
from  these  pyramidal  ends  the  cells  or  fibres,  more  attenuated, 
pass  perpendicularly  outward  through  the  various  layers  to 
the  external  limiting  membrane,  giving  off  lateral  sustentacular 
branches  and  reticula ;  in  the  inner  nuclear  layer  the  fibre  ex- 
hibits a  nucleus,  and  externally  the  fibres  terminate  in  fine 
processes  which  pierce  the  external  limiting  membrane  and 
lie  among  the  bases  of  the  rods  and  cones.  Other  branched 
neuroglia-cells  lie  in  the  outer  reticular  layer. 

The  nerve-fibre  layer  is  made  up  of  non-medullated  nerve- 


THE  INNER  EETICULAR  LAYER. 


231 


fibres  derived  and  radiating  from  the  optic  nerve  and  also 
connected  with  the  retinal  nerve-cells. 

The   ganglion-cell  layer  consists  of  rather  scattered  large 
rounded  nerve-cells  with  numerous  branched  processes. 


FIG.  92. 


Diagrammatic  section  of  human  retina  (Schultze). 

The  inner  reticular  (or  molecular)  layer  is  a  broad  non- 
nucleated  zone  formed  by  a  delicate  fibrous  reticulum  derived 


232  THE  NERVOUS  SYSTEM. 

from  the  neuroglia-elements  and  the  processes  of  neighboring 
nerve-cells. 

The  inner  nuclear  (or  granular)  layer  is  a  narrower  zone 
crowded  with  nerve-cells  having  prominent  nuclei ;  the  nuclei 
of  Miiller's  fibres  are  also  in  this  layer. 

The  outer  reticular  (or  molecular)  layer  is  a  narrow  reticu- 
lum  of  neuroglia- fibres  and  nerve-cell  processes. 

The  outer  nuclear  (or  granular)  layer  is  a  broad  zone  crowded 
with  the  nuclei  and  the  lower  portions  of  the  rod  and  cone  cells. 

The  external  limiting  membrane  is  a  thin  perforated  mem- 
brane, through  the  openings  of  which  pass  the  rod  and  cone 
cells. 

The  layer  of  rods  and  cones  is  composed  of  the  portions  of 
the  rod  and  cone  cells  external  to  the  limiting  membrane. 
The  rod  and  cone  cells  are  elongated  neuro-epithelium  cells, 
arranged  perpendicularly,  divided  into  two  zones  by  the  limit- 
ing membrane,  their  nucleated  portions  occupying  the  outer 
nuclear  layer  and  their  terminal  portions  forming  the  layer  of 
rods  and  cones. 

The  portion  of  the  rod-visual  cells  in  the  nuclear  layer  is  a 
slender  fibre,  the  "  rod-fibre,"  with  a  bulbous  expansion  con- 
taining the  transversely  banded  nucleus.  The  portion  external 
to  the  limiting  membrane,  or  "  rod,"  consists  of  two  segments, 
the  inner  one  continuous  with  the  rod-fibre  being  fusiform, 
and  granular  or  fibrillated  (especially  in  its  outer  part) ;  while 
the  outer  segment  is  a  slender  cylinder  containing  rhodopsin 
and  possessing  special  staining  properties. 

The  portion  of  the  cone-visual  cells  outside  of  the  limiting 
membrane,  or  the  "cone,"  also  consists  of  two  segments,  an 
outer  part  similar  to  the  corresponding  portion  of  the  rods  ex- 
cept that  it  is  shorter,  conical,  and  contains  no  rhodopsin;  and 
an  inner  broad  fusiform  portion,  fibrillated  or  granular  exter- 
nally. The  portion  of  the  cone-cell  within  the  outer  nuclear 
zone  consists  of  a  slender  " cone-fibre"  with  an  expansion, 
containing  the  nucleus,  next  to  the  limiting  membrane  and 
uniting  with  the  fusiform  segment.  The  rod-cells  consider- 
ably outnumber  the  cone-cells. 

The  pigment-layer  of  the  retina,  lying  next  to  the  vitreous 
membrane  of  the  choroid,  consists  of  a  single  layer  of  hex- 
agonal columnar  epithelium-cells,  with  their  nuclei  next  to  the 


THE  EAR.  233 

cboroid,  and  their  inner  portions,  adjoining  and  between  the 
rods  and  cones,  studded  with  pigment-granules. 

In  the  macula  lutea  the  rods  are  absent  and  some  of  the 
retinal  layers  are  thickened  and  pigmented  yellow.  At  the 
fovea  centralis  only  the  layer  of  cone-cells  is  present  in  full 
development,  the  layers  in  front  of  it — i.  e.,  toward  the  centre 
of  the  globe — being  greatly  thinned  and  nearly  abolished. 

The  eyelids  (upper)  are  covered  anteriorly  with  thin  skin, 
beneath  which  is  areolar  subcutaneous  tissue  containing  little 
or  no  fatty  tissue.  Next  to  this  is  a  layer  of  striated  muscle, 
the  orbicularis  palpebrarum.  Posterior  to  this  is  a  zone  of 
loose  connective  tissue,  the  fascia  palpebr  alls,  into  which  the 
insertion  of  the  levator  palpebra?  merges.  Posterior  to  this 
and  next  to  the  conjunctiva  is  a  dense  fibrous  plate,  the 
tarsus,  in  which  are  imbedded  a  number  of  modified  seba- 
ceous glands,  the  Meibomian  glands,  each  consisting  of  an 
elongated  series  of  follicles  opening  into  a  duct  which  dis- 
charges at  the  margin  of  the  lid. 

In  the  upper  part  of  the  tarsal  plate,  especially  toward  the 
nose,  are  small  accessory  lachrymal  glands.  The  posterior 
surface  of  the  lid  is  covered  by  conjunctiva,  composed  of 
stratified  columnar  epithelium  on  a  tunica  propria,  which  lies 
next  to  the  tarsus. 

At  the  margin  of  the  lid  is  a  row  of  stiff  hairs,  the  eye- 
lashes, the  follicles  of  which  separate  the  margin  of  the 
orbicularis  palpebrarum  from  the  main  portion  of  the  muscle  ; 
behind  the  lashes  are  modified  sweat-glands  (Moll's  glands) ; 
and  still  farther  posteriorly  are  the  openings  of  the  Meibomian 
glands. 

The  lachrymal  gland  is  a  racemose  gland  of  the  serous  type, 
the  saccules  of  which  empty  into  a  number  of  independent 
and  separate  outlet-ducts.  The  lachrymal  canals  are  tubes 
lined  with  mucous  membrane  connecting  the  conjunctive  with 
the  nasal  fossa?. 

The  Ear. 

The  ear  is  a  complicated  structure  associated  with  the  term- 
ination of  the  nerves  of  hearing,  and  \vith  the  sense  of 
position.  It  is  divided  into  the  external,  middle,  and  internal 
ear. 


234  THE  NERVOUS  SYSTEM. 

External  ear :  The  auricle  consists  of  a  basis  of  elastic 
cartilage  covered  with  subcutaneous  tissue  and  skin — except 
the  lobule,  whose  interior  is  occupied  by  fibrous  tissue. 

The  outer  (cartilaginous)  portion  of  the  external  auditory 
canal  is  lined  with  skin,  which  is  very  thick  and  contains 
hairs,  their  sebaceous  glands,  and  ceruminous  glands,  a  modi- 
fied form  of  sweat-gland.  This  portion  of  the  canal  has  a 
basis  of  elastic  cartilage  beneath  the  subcutaneous  tissue. 

The  inner  (bony)  portion  of  the  auditory  canal  is  mostly 
lined  with  thin  skin  containing  no  glands  or  hair. 

The  middle  ear  (or  tympanum)  is  a  cavity  filled  with  air, 
communicating  with  the  Eustachian  tube  anteriorly  and  the 
mastoid  sinuses  posteriorly,  and  crossed  by  a  chain  of  ossicles 
connecting  the  tympanic  membrane  with  the  fenestra  ovalis. 

Its  walls  are  formed  by  bone,  the  tympanic  membrane,  and 
the  secondary  tympanic  membrane,  all  lined  with  mucous 
membrane. 

The  mucous  membrane  is  thin  and  closely  connected  with 
the  underlying  periosteum  ;  it  is  reflected  over  the  surface  of 
the  ossicles  and  mastoid  sinuses  and  is  continuous  with  the 
mucous  lining  of  the  Eustachian  tube.  Its  superficial  layer 
consists  of  low  columnar  epithelium,  in  places  ciliated,  in 
other  places  non-ciliated.  Anteriorly  are  scattered  tubular 
glands. 

The  tympanic  membrane  is  made  up  of  an  intermediate 
fibrous  lamina  covered  externally  with  skin  and  internally 
with  a  portion  of  the  mucosa  lining  the  middle  ear;  the  sur- 
face epithelium-cells  of  the  latter  are  low  and  non-ciliated. 

The  secondary  tympanic  membrane  closes  the  fenestra 
rotunda,  and  consists  of  an  intermediate  fibrous  lamina, 
covered  externally  with  mucous  membrane  (having  non-ciliated 
low  epithelium)  continuous  with  the  mucosa  of  the  middle  ear, 
and  internally  with  endothelium  and  subendothelial  tissue 
continuous  with  that  lining  the  internal  ear. 

The  Eustachian  tube  is  an  open  canal  connecting  the  middle 
ear  with  the  pharynx.  Its  walls  are  formed  of  bone,  cartilage 
(partly  hyaline,  partly  elastic),  and  fibrous  tissue,  lined  with 
mucous  membrane  continuous  with  that  of  both  the  middle 
ear  and  pharynx.  The  surface  cells  of  this  mucosa  are  strati- 
fied ciliated  epithelium.  In  its  upper  portion  the  mucous 


THE   UTRICLE  AND  SACCULE.  235 

lining  is  thin  ;  in  the  lower  or  pharyngeal  portion  it  is  thicker, 
underlaid  with  areolar  submucous  tissue,  and  contains  mucous 
glands  and  lymphoid  tissue. 

The  internal  ear  (or  labyrinth)  contains  the  terminal  appa- 
ratus of  the  auditory  nerve,  and  occupies  a  tortuous  bony 
cavity  (the  "  bony  labyrinth")  in  the  temporal  bone. 

The  bony  labyrinth  has  three  divisions — the  cochlea,  semi- 
circular canals,  and  vestibule,  the  latter  connecting  the  two 
others. 

Within  the  bony  labyrinth  is  a  membranous  sac,  the  "  mem- 
branous labyrinth"  containing  "  endolymph"  and  correspond- 
ing in  general  to  the  windings  of  the  bony  labyrinth. 

The  membranous  labyrinth  is  separated  from  the  bony 
walls  in  most  places  by  a  peripheral  lymph-space,  lined  with 
endothelium  and  filled  with  "perilymph." 

The  bony  labyrinth  is  lined  with  periosteum,  covered  in 
general  with  endothelium. 

The  membranous  labyrinth  consists  of  the  utricle  and 
saccule,  situated  in  the  vestibule,  the  membranous  semicircular 
canals,  and  the  scala  media  of  the  cochlea. 

The  neuro-epithelial  terminals  of  the  auditory  nerve  are 
situated  on  the  inner  surface  of  the  membranous  labyrinth, 
and  consist  of  the  maculce  acusticce  of  the  utricle  and  saccule, 
the  cristce  acusticce  of  the  ampullae  of  the  semicircular  canals, 
and  the  organ  of  Corti. 

The  vestibule  is  a  bony  chamber  connecting  the  semicircular 
canals  with  the  cochlea.  It  contains  the  utricle  and  saccule, 
which  are  separated  from  the  bony  walls  by  the  perilymph- 
space.  This  space  is  in  relation  with  the  middle  ear  by  the 
fenestra  ovalis,  which  is  closed  by  the  base  of  the  stapes. 

The  utricle  and  saccule  are  rounded  membranous  sacs,  com- 
municating with  each  other  by  a  small  indirect  canal,  the 
"  ductus  endolymphaticus."  Their  walls  are  formed  by  a 
fibrous  membrane  lined  internally  with  simple  squamous  epi- 
thelium, altered  to  columnar  in  the  maculae  acustica3 ;  exter- 
nally they  are  covered  with  endothelium.  They  are  connected 
with  the  periosteum  of  the  bony  walls  by  fibrous  bands,  which 
cross  the  peri  lymph-space  and  convey  vessels  and  nerves. 
The  utricle  opens  into  the  semicircular  canals;  the  saccule 
communicates  through  the  small  "  canalis  reuniens"  with  the 


236  THE  NERVOUS  SYSTEM. 

scala  media,  or  cochlear  portion  of  the  membranous  laby- 
rinth. 

The  utricle  and  saccule  each  possesses  on  its  inner  surface 
a  neuro-epithelial  terminal,  called  the  macula  acustica. 

The  macula  is  an  area  covered  with  columnar  epithelium- 
cells  of  two  kinds  :  (a)  "  sustentacular"  or  "  fibre-cells,"  long, 
slender  cells,  between  which  are  situated  (6)  "  hair-cells,"  pyri- 
form  cells  with  filamentary  processes  or  cilia  projecting  from 
their  free  ends.  Terminal  nerve-fibrils  from  the  auditory 
nerve  are  in  relation  with  the  bases  and  sides  of  the  hair-cells. 
The  surface  of  the  macula  is  covered  with  a  matrix  or  layer 
containing  minute  calcium-carbonate  crystals,  or  "otoliths." 

The  semicircular  canals,  opening  from  the  utricle,  are  mem- 
branous tubes  formed  of  a  fibrous  membrane  lined  internally 
by  simple  squamous  epithelium  (except  over  the  cristas)  and 
externally  with  endothelium,  and  separated  from  the  bony 
walls  by  the  perilymph-space.  Each  membranous  canal  has 
an  enlargement  or  ampulla  at  one  of  its  junctions  with  the 
utricle,  and  on  the  inner  surface  of  each  of  the  three  ampulla; 
is  situated  a  neuro-epithelial  structure  called  the  crista  acustica. 

These  cristce  are  ridges  covered  with  columnar  epithelium- 
cells  of  two  kinds,  similar  to  those  of  the  maculae  acusticse : 
(a)  "sustentacular"  or  " fibre-cells,"  long,  slender  columnar 
cells,  between  which  are  (6)  "  hair-cells,"  shorter  cells  with 
long  hairs  or  cilia  projecting  from  their  free  ends  into  the 
ampulla?.  Nerve-fibrils  terminate  among  the  hair-cells.  There 
is  no  layer  of  otoliths  over  the  cristaB. 

The  cochlea  consists  of  three  passages,  the  scala  vestibuli, 
scala  media,  and  scala  tympani,  wound  spirally  two  and  a 
half  turns  around  a  central  column  or  "modiolus"  (Fig.  93). 

The  scala  media  is  the  cochlear  portion  of  the  membranous 
labyrinth  ;  the  other  two  scalse  represent  the  perilymph-spaces. 

The  scala  vestibuli  and  scala  tympani  are  lined  with  endo- 
thelium, and  are  separated  from  each  other  externally  by  the 
scala  media  and  internally  by  the  "lamina  spiralis,"  a  spiral 
bony  ledge  projecting  from  the  modiolus. 

The  scala  vestibuli  is  the  uppermost  of  the  three  cochlear 
passages,  and  opens  below  into  the  perilymph-space  of  the 
vestibule;  at  the  apex  of  the  cochlea  it  communicates  with 
the  scala  tympani.  The  lower  end  of  the  latter  is  blind,  but 


THE  SCALA   MEDIA. 


237 


communicates  with  the  middle  ear  by  the  fenestra  rotunda, 
closed  by  the  secondary  tympanic  membrane. 

The  scala  media  (canalis  or  ductus  cochlearis)  is  the  middle 
passage  of  the  cochlea ;  it  ends  blindly  above,  and  communi- 
cates below  with  the  saccule  by  the  small  canalis  reuniens. 


FIG.  93. 


Radial  section  of  portion  of  cochlea  of  guinea-pig  (Klein),  a,  scala  vestibuli ;  6, 
scala  tympani :  c,  scala  media ;  d,  rnembrana  tectoria  ;  h,  membrane  of  Reiss- 
ner ;  j,  organ  of  Corti,  resting  on  basilar  membrane  ;  k,  stria  vascularis  ;  I,  liga- 
mentum  spirale;  m,  limbus ;  n,  nerve-fibres  in  lamina  spiralis ;  o,  spiral  gan- 
glion ;  p,  nerve-fibres  in  modiolus ;  s,  bony  wall. 

The  upper  wall  of  the  scala  media,  separating  it  from  the 
scala  vestibuli,  is  formed  by  the  membrane  of  Reissner,  a  very 
thin  fibrous  membrane  lined  on  the  vestibular  surface  with 
endothelium,  and  on  the  surface  within  the  scala  media  with 
simple  squamous  epithelium. 


238  THE  NERVOUS  SYSTEM. 

The  outer  wall  of  the  scala  media  is  lined  with  a  single 
layer  of  epithelium-cells,  varying  from  squamous  to  columnar, 
which  rest  on  the  ligamentum  spirale,  a  fibrous  cushion  lying 
against  the  bony  walls  on  the  outer  side  of  the  cochlea;  a 
portion  of  this  outer  wall  ("  stria  vascularis ")  is  very 
vascular. 

The  floor  or  lower  wall  of  the  scala  media  is  formed  by  the 
margin  or  limbus  of  the  lamina  spiralis,  the  basilar  membrane, 
and  columnar  and  neuro-epithelium  (the  organ  of  Corti)  rest- 
ing on  the  latter.  The  margin  of  the  bony  spiral  lamina  is 
thickened  by  the  development  on  its  upper  surface  of  a  mass 
of  fibrous  tissue,  the  whole  forming  the  limbus. 

The  outer  projecting  aspect  of  the  limbus  is  hollowed 
into  a  groove,  the  sulcus  spiralis,  the  upper  lip  of  which 
is  called  the  labium  vestibulare,  the  lower  lip  the  labium  tym- 
panicum. 

The  labium  vestibulare  is  divided  by  clefts  into  fine  proc- 
esses called  the  "  auditory  teeth." 

The  membrana  basilaris  is  a  connective-tissue  lamina  ex- 
tending from  the  labium  tympanicum  of  the  limbus  across  to 
the  ligamentum  spirale  on  the  outer  wall,  shutting  off'  the 
scala  media  from  the  scala  tympani ;  it  is  lined  underneath 
(within  the  scala  tympani)  with  endothelium,  while  its  upper 
surface  is  covered  with  columnar  epithelium  and  the  neuro- 
epithelium  constituting  the  organ  of  Corti. 

The  upper  surface  of  the  limbus  is  lined  with  simple  squam- 
ous epithelium  continuous  with  that  lining  the  membrane  of 
Reissner. 

The  sulcus  spiralis  is  lined  with  a  layer  of  columnar  epithe- 
lium-cells, which  extend  to  the  inner  hair-cells  or  inner  margin 
of  the  organ  of  Corti. 

The  organ  of  Corti  (Fig.  94) :  These  inner  hair-cells 
comprise  a  single  row  of  columnar  epithelium-cells,  with  a 
number  of  filaments  or  hairs  projecting  from  their  free  ends ; 
they  are  adjacent  to  and  on  the  inner  side  of  the  pillars  of 
Corti,  their  attached  ends  not  extending  to  the  basilar  mem- 
brane. 

The  pillars  or  rods  of  Corti  are  two  rows  of  elongated 
epithelial  elements,  the  lower  ends  of  which  rest  on  the  basilar 
membrane  some  distance  apart,  and  whose  upper  ends  are 


THE  ORGAN  OF  CORTI. 


239 


articulated  together,  meeting  like  the  rafters  of  a  roof;  they 
inclose  a  lymph-space  or  passage,  the  "tunnel  of  Corti," 
which  follows  the  spiral  windings  of  the  cochlea. 

These  pillar-cells,  inner  and  outer,  have  slender  shafts  of  a 
firm  substance,  with  enlarged  extremities,  and  with  nuclei  and 
some  ordinary  protoplasm  at  their  lower  ends. 

External  to  the  pillars  of  Corti  are  three  or  four  rows  of 
outer  hair-cells,  columnar  epithelium-cells  with  hairs  projecting 
from  their  exposed  ends.  They  extend  from  the  upper  sur- 

Fio.  94. 


Organ  of  Corti,  human,  in  cross-section  (Retzius). 

face  of  the  organ  of  Corti  only  about  half-way  to  the  basilar 
membrane. 

The  outer  hair-cells  alternate  with  and  are  supported  by  the 
cells  of  DeiterSj  long  columnar  sustentacular  epithelium-cells, 
somewhat  like  the  pillar-celis,  and  with  their  bases  separated 
by  slight  intervals,  the  "spaces  of  Nuel." 

The   upper  ends  of  the  pillar-cells   and  cells  of  Deiters 


240  THE  NERVOUS  SYSTEM. 

exhibit  a  cuticular  structure  (the  "membrana  reticularis "), 
with  openings  for  the  ends  of  the  hair-cells. 

External  to  the  outer  hair-cells  is  a  zone  of  long  colum- 
nar epithelium-cells  (cells  of  Hensen),  which  externally  be- 
come shorter  and  merge  into  a  zone  of  low  columnar  epi- 
thelium (cells  of  Claudius)}  the  latter  occupy  the  outermost 
part  of  the  basilar  membrane  and  are  continuous  with 
the  squamous  epithelium  lining  the  outer  wall  of  the  scala 
media. 

Attached  to  the  labium  vestibulare  of  the  limbus  is  a  soft 
structure,  the  membrana  tectoria,  which  extends  outward  over 
the  organ  of  Corti. 

Nerve-fibrils  from  the  cochlear  branch  of  the  auditory  nerve 
terminate  among  the  hair  cells  of  the  organ  of  Corti.  The 
cochlear  nerve  lies  in  the  modiolus,  and  sends  branches 
laterally  into  the  lamina  spiralis,  where  they  are  associated 
with  nerve-cells  to  form  the  spiral  ganglion;  from  the 
ganglion  the  nerve-fibres  pass  out  into  the  organ  of  Corti 
at  the  labium  tympanicum. 


PATHOLOGY. 


PATHOLOGY. 


INTRODUCTORY. 


Pathology  (nado^,  disease,  and  ^oc,  discourse)  is  the  science 
which  treats  of  animal  and  vegetable  life  under  abnormal 
conditions — i.  e.,  the  science  of  disease.  It  is  that  branch 
of  medicine  which  considers  abnormalities  of  structure  and 
function,  the  causes  thereof,  and  the  relation  of  these  changes 
to  the  clinical  aspects  of  disease  produced  thereby. 

Human  pathology  then  includes  the  study  of  etiology  or  the 
causes  of  disease ;  morbid  anatomy — macroscopical  and  micro- 
scopical ;  and  morbid  or  pathological  physiology.  With  these 
must  always  go  hand  in  hand  clinical  observation,  in  order 
that  a  true  conception  may  be  formed  of  disease-processes.  As 
our  knowledge  of  anatomy  is  more  advanced  than  that  of 
physiology,  so  our  knowledge  of  morbid  anatomy  is  more 
perfect  than  that  of  morbid  physiology. 

The  importance  of  this  branch  of  medicine  cannot  be  over- 
estimated by  the  student ;  it  is  the  one  sure  basis  for  diag- 
nosis, prognosis,  and  rational  therapeusis.  Some  of  the 
greatest  additions  to  medical  knowledge  have  been  made  by 
the  study  of  morbid  anatomy  in  conjunction  with  clinical 
observation.  Apoplexy  was  supposed  to  be  due  to  the  inter- 
ruption of  certain  imaginary  spirits  till  Wepfer  showed  cere- 
bral hemorrhage  to  be  the  cause  in  a  large  number  of  cases. 
In  this  manner  Bright  demonstrated  the  relation  between 
certain  alterations  in  the  kidneys,  and  albnminuria  and  dropsy. 
Typhoid  and  typhus  fevers  were  regarded  as  identical  until 
1836,  when  a  post-mortem  study  of  the  lesions  present  proved 
the  contrary.  The  mediaeval  physician  rarely  endeavored  to 
locate  the  seat  of  a  disease — certainly  not  beyond  assigning 
it  to  one  of  the  larger  cavities  of  the  body,  i.  e.,  the  head, 

243 


244  INTRODUCTORY. 

chest,  or  abdomen.  In  fact,  but  little  was  added  to  the  teach- 
ings of  Hippocrates  (460  B.  c.)  and  Galen  (130-200  A.  D.) 
until  about  1500,  when  the  first  post-mortems  began  to  be 
made. 

During  the  sixteenth  century  Vesalius,  Sylvius,  and  their 
successors  laid  the  foundation  of  modern  medicine  by  the 
systematic  study  of  anatomy,  to  which  was  added  by  Harvey 
and  others  during  the  seventeenth  century  such  essential 
physiological  data  as  the  function  of  the  heart,  circulation  of 
blood,  and  the  mechanism  of  respiration. 

Morgagni  (1682-1771)  was  the  first  to  attempt  to  localize 
a  disease-process  in  a  particular  organ  and  wrote  the  first 
great  treatise  on  morbid  anatomy.  The  first  illustrated  work 
on  the  subject  was  by  Baillie  (1799),  who  drew  his  inspiration 
and  material  from  John  Hunter.  It  was  not  until  the  early 
part  of  this  century,  however,  that  there  was  a  real  beginning 
in  its  study.  But  there  were  limitations  to  gross  morbid 
anatomy. 

Histology  received  its  first  impulse  from  Bichat,  to  whom 
is  due  also  a  step  in  advance  in  pathology ;  he  declared  that 
the  ultimate  seat  of  a  disease  might  be  a  particular  tissue 
of  an  organ.  Though  the  microscope  had  been  employed 
in  the  seventeenth  century  by  Leuweenhoeck  and  Malpighi, 
it  was  as  recent  as  1847  that  the  foundation  of  normal  his- 
tology was  laid  by  the  work  of  Schleiden  on  "Vegetable 
Pathology/'  and  later  of  Schwann  on  the  "  Comparison  of 
the  Cellular  Structure  of  Vegetables  and  Animals." 

Modern  or  cellular  pathology  dates  from  the  teachings  of 
Virchow  (1858),  to  whom  credit  is  due,  more  than  to  any 
other  one  man,  for  elevating  the  study  of  disease  to  a  place 
in  the  science  of  biology.  The  cellular  theory  of  life  led 
naturally  to  the  cellular  theory  of  disease.  A  comparison  of 
the  lower  forms  of  animal  and  vegetable  life  with  the  cells 
of  higher  ones  convinced  Virchow  that  if  the  former  are  in- 
dividuals, the  latter  must  be  so  regarded  also.  For  the  axiom 
of  Harvey,  "Omne  vivum  ex  ovo,"  he  substituted  the  dictum 
"  Omnis  cellula  a  cellula "  ;  he  applied  the  histological  dis- 
coveries of  Schleiden  and  Schwann  to  pathology  and  showed 
that  the  essence  of  disease  is  the  altered  cell, — the  histological 
and  vital  unit  of  all  organized  tissue, — and  called  attention  to 


INTRODUCTORY.  245 

the  minute  changes  which  it  undergoes  in  disease.  The  cellu- 
lar theory  has  done  for  pathology  what  the  atomic  theory  has 
for  chemistry. 

Medical  knowledge  has  been  advanced  more  in  recent 
years  by  experimental  pathology  than  by  any  other  method  of 
investigation.  Though  Galen  is  said  to  have  used  living 
animals  for  pathological  experimentation,  the  foundation  of 
these  methods  and  the  revival  of  pathology  in  general  were 
due  to  John  Hunter  in  the  latter  part  of  the  last  century.  To 
bacteriology,  one  branch  of  experimental  pathology,  we  owe 
our  knowledge  of  the  microbic  cause  of  many  of  the  infec- 
tious diseases — the  germ-theory,  in  its  practical  results  having 
almost  revolutionized  medicine  and  surgery  within  a  quarter 
of  a  century. 

Disease  is  a  deterioration  in  or  deviation  from  the  normal 
standard  called  health.  Probably  all  deviations  of  function 
from  normal  are  dependent  on  some  alteration  in  structure ; 
when  our  present  methods  fail  to  discover  such  anatomical 
changes  the  disease  is  said  to  be  functional,  in  contradistinction 
to  organic  disease,  in  which  such  alterations  can  be  demon- 
strated. There  is  no  sharp  line  of  demarcation  between 
health  and  disease,  the  one  passing  imperceptibly  into  the 
other. 

Heredity  plays  a  most  important  part  in  the  causation  of 
disease  ;  it  is  not  uncommon  to  see  reproduced  in  a  family  the 
same  infirmities  or  diatheses  for  many  generations — and  the  ill 
results  of  consanguineous  marriage  are  a  matter  of  common 
knowledge. 

Susceptibility  to  various  diseases  varies  greatly  in  different 
individuals— the  determining  factors  being  inherited  in  some 
cases  and  acquired  in  others,  and  temporary  or  permanent  in 
their  duration.  The  susceptibility  of  children  of  tubercular 
parents  to  tuberculosis  is  observed  with  great  frequency  ; 
without  such  inherited  tendencies  however,  during  some  tem- 
porary impairment  of  health,  there  may  be  an  acquired 
susceptibility  to  the  disease,  which,  for  instance,  is  especially 
common  after  measles  in  children — the  attack  either  preparing 
a  soil  particularly  inviting  to  the  tubercle  bacilli  or  reducing 
the  patient's  resisting  powers  to  such  an  extent  that  they  are 
not  able  to  cope  with  the  invasion  of  these  micro-organisms 


246  INTRODUCTORY. 

successfully,  as  would  be  the  case  wer6  they  not  temporarily 
so  reduced. 

The  well-known  insusceptibility  of  the  negro  to  yellow  fever 
and  malaria  are  examples  of  the  comparative  immunity 
which  a  race  may  enjoy  ;  and  among  the  lower  animals  the 
same  thing  is  noted  of  different  species — for  instance,  the  frog 
is  immune  against  infection  with  anthrax,  while  the  mouse, 
guinea-pig,  and  many  other  animals  are  extremely  susceptible. 

The  comparative  insusceptibility  of  an  individual  to  a 
second  attack  of  such  diseases  as  smallpox,  scarlet  fever,  and 
measles  is  an  example  of  acquired  immunity.  Such  immunity 
may  be  conferred  artificially,  as  is  witnessed  daily  in  the 
practice  of  vaccinating  against  smallpox. 

Equally  striking  is  the  varying  susceptibility  of  an  indi- 
vidual at  various  times  in  his  life  to  the  same  disease. 

Exciting  causes  are  those  immediately  responsible  for  the 
onset  of  the  disease  ;  among  these  may  be  mentioned  trauma, 
exposure  to  heat  and  cold,  poisons,  and,  by  far  the  most 
important  of  all,  animal  and,  more  especially,  vegetable 
parasites — of  which  latter  bacteria  are  the  most  important. 

But  a  discussion  of  these  topics  would  lead  far  beyond  the 
limits  assigned  us  and  must  be  thus  dismissed.  The  study  of 
bacteriology  has  grown  within  a  few  years  to  large  propor- 
tions— and  volumes  have  been  written  concerning  animal 
parasites. 

Pathology,  or  pathological  anatomy,  with  which  the  following 
pages  are  more  especially  concerned,  may  be  divided  for  con- 
venience into  two  sections — one,  the  general  aspects  of  disease- 
processes  without  reference  to  any  individual  part ;  and  the 
other,  diseases  of  special  organs  and  systems. 


GENERAL  PATHOLOGY. 


CHAPTER    I. 

PATHOLOGY  OF  THE  BLOOD  AND  CIRCULATION. 

INFLAMMATION. 

Inflammation  is  undoubtedly  the  most  important  and  most 
common  phenomenon  in  pathology.  It  is  convenient  to  con- 
sider it  as  an  entity  rather  than  a  series  of  morbid  phenomena. 
Ko  subject  in  medicine  is  more  deserving  the  student's  atten- 
tion. It  underlies  a  majority  of  the  diseases  to  which  man  is 
heir.  In  all  ages  its  consideration  has  so  dominated  the  doc- 
trines and  medical  philosophy  of  the  time  that  it  might  well 
be  said  to  form  the  basis  of  the  theory  and  practice  of  medi- 
cine and  surgery. 

The  term  "  inflammation  "  was  created  in  the  very  infancy 
of  science,  indicating  that  the  part  involved  seemed  to 
burn — to  be  inflamed.  The  cardinal  symptoms  which  are 
familiar  to  all  to-day  were  described  two  thousand  years  ago 
by  Celsus — tumor,  rubor,  calor,  and  dolor.  The  interpretation 
of  these  symptoms  and  conception  of  the  underlying  processes 
varied  as  this  or  that  symptom  was  considered  of  the  greatest 
importance.  Humoral  doctrines  perished  with  Harvey's 
discovery  of  the  circulation  of  the  blood,  the  advances  made 
in  chemistry,  and  the  systematic  study  of  morbid  anatomy. 
Since  then  the  study  of  inflammatory  lesions  has  followed  step 
by  step  the  progress  in  the  biological  sciences. 

Definition :  We  may  attempt  to  define  inflammation  as  the 
ensemble  of  the  degenerative  and  reactionary  phenomena  oc- 
curring in  living  tissues  as  the  result  of  mechanical,  infectious, 
and  toxic  injuries. 

Early  experiments :  John  Hunter,  a  century  ago,  was  the 
first  to  throw  experimental  light  upon  this  subject  of  in- 

247 


248     PATHOLOGY  OF  THE  BLOOD  AND  CIRCULATION. 

flammation.  He  froze  the  ear  of  a  rabbit  and  then  allowed  it 
to  thaw,  thus  exciting  considerable  inflammation.  The  animal 
was  killed  when  the  process  was  at  its  height,  the  bloodves- 
sels of  the  head  injected,  and  the  ears  removed  and  dried. 
The  unin flamed  ear  was  clear  and  transparent,  and  the  blood- 
vessels easily  seen ;  the  inflamed  ear  was  thick  and  opaque, 
and  the  arteries  much  enlarged. 

A  few  years  later  very  numerous  indeed  are  the  papers  and 
monographs  describing  the  changes  in  the  size  of  the  blood- 
vessels in  an  inflamed  animal  membrane  studied  under  the 
microscope.  A  frog  was  restrained  in  a  muslin  bag  and  to 
the  web  of  the  foot — less  frequently  to  its  mesentery — or  to 
the  web  of  the  foot  of  a  young  duck  similarly  restrained — 
various  irritants  were  applied  and  the  results  noted  under  the 
microscope.  The  increased  size  in  the  capillary  bloodvessels 
was  thus  observed  in  the  affected  area,  and  further  a  marked 
slowing  in  the  rapidity  of  the  blood-current. 

By  184-0  we  find  the  description  much  more  complete. 
Addison  and  others  carefully  described,  in  addition,  an  axial 
stream  of  red  blood-cells  and  a  much  more  slowly  moving 
peripheral  stream  in  which  were  found  the  leukocytes ;  and 
as  the  velocity  of  the  circulation  became  less  and  less  the 
great  accumulation  of  the  latter  along  the  inner  wall  of  the 
vessels  was  noted.  Addison  maintained  the  identity  of  the 
leukocyte  and  pus-cell ;  and  even  the  passage  of  the  leukocytes 
through  the  bloodvessel-walls  was  described,  but  failed  to  at- 
tract much  attention ;  a  phenomenon  which,  since  the  work 
of  Cohnheirn,  twenty-eight  years  later,  has  been  studied  with 
great  interest. 

The  experiments  of  Cohnheim  (1867),  though  they  simply 
duplicated  the  experimental  studies  of  earlier  observers  on 
living  animal  membranes,  were  of  the  greatest  importance,  for 
to  him  undoubtedly  all  credit  is  due  for  our  knowledge  of  the 
migration  of  the  leukocytes,  the  announcement  of  which  came 
as  a  surprise  to  all. 

Microscopical  appearances  of  inflamed  animal  membranes : 
First  stage:  Dilatation  of  vessels;  acceleration  of  blood-current. 
When  the  mesentery  of  a  curarized  frog  is  exposed  under  the 
microscope  there  is  soon  noted  a  dilatation  of  the  arteries  and 
then  of  the  veins,  and  to  a  very  much  less  degree  of  the  capil- 


IX  FLA  MM  A  TION. 


249 


laries ;  by  the  end  of  fifteen  or  twenty  minutes  it  may  be  very 
decided,  most  apparent,  however,  in  the  arteries.  At  the  same 
time  there  is  a  marked  acceleration  of  the  blood-current,  equally 
pronounced  in  arteries,  veins,  and  capillaries.  The  stage  of 

POSITIONS  OF  THE  CORPUSCLES  IN  CIRCULATING  BLOOD  (EBERTH  AND  SCHIMMELBUSCH). 

FIG.  95. 


Appearance  when  the  velocity  of  the  circulation  is  normal,  a,  axial  column 
of  corpuscles,  both  red  and  white,  in  such  rapid  movement  that  individual 
corpuscles  cannot  be  distinguished.  Occasionally  a  white  corpuscle  is  thrown 
from  the  axial  mass  and  appears  in  the  plasmic  zone  6. 

FIG.  96. 


Appearance  when  the  velocity  of  the  circulation  is  moderately  reduced.    The  zone 
b  contains  numerous  leukocytes. 

FIG.  97. 


lYS--- 


Appearance  when  the  current  of  blood  is  sluggish,  a,  red  corpuscles,  still  in  the 
axis  ;  b,  peripheral  zone,  containing  leukocytes,  d,  and  blood-plates,  c. 

When  stasis  is  fully  established  the  red  corpuscles  also  invade  the  peripheral  zone. 
The  figures  are  from  observations  made  on  the  vessels  of  a  dog's  omentum 

during  life. 

acceleration  in  the  blood-current  will  never  last  more  than  one 
or  two  hours,  by  the  end  of  which  time  the  vessels  have  be- 
come twice  their  normal  diameter. 

Second  stage:  Retardation  of  blood-current;   margination 


250     PATHOLOGY   OF  THE  BLOOD  AND   CIRCULATION. 

of  the  leukocytes.  The  acceleration  of  the  blood-current, 
which  may  be  only  transitory,  is  followed  by  its  progressive 
retardation  until  the  vessels  are  engorged  with  blood.  The 
current  becomes  slower  and  slower,  until  finally  each  individual 
red  blood-cell  can  be  recognized,  and  every  heart-beat  causes 
sudden  jerks  in  the  flow. 

But  soon  one's  attention  is  fixed  upon  tine  veins.  Normally 
there  are  only  a  few  leukocytes  to  be  seen  in  the  periphery  of 
the  current,  where  they  are  occasionally  driven  from  the  axial 
stream  of  red  blood-cells  by  reason  of  their  lower  specific 
gravity.  But  now  the  number  of  leukocytes  in  this  peripheral 
stream  is  rapidly  increasing.  They  lag  behind  the  still  quite 
rapidly  moving  axial  stream  of  z*ed  blood-cells,  momentarily 
clinging  from  place  to  place  as  they  are  carried  on.  This  same 
tendency  is  also  seen  in  the  capillaries. 

In  the  arteries,  with  each  cardiac  diastole  a  number  of  leu- 
kocytes roll  into  the  peripheral  stream,  only  to  be  swept  back 
into  the  axial  stream  with  the  next  systole.  Finally  the  inner 
surface  of  the  walls  of  the  veins  is  almost  lined  by  a  layer 
of  leukocytes.  This  phenomenon  of  margination  was  described 
by  all  the  earlier  observers  (Figs.  95,  96,  and  97). 

Third  stage:  Diapedesis;  interstitial  exudation.  Margina- 
tion is  followed,  sometimes  immediately,  sometimes  only  after 
an  hour  or  more,  by  diapedesis  or  migration  of  the  leukocytes. 
There  appears  on  the  external  surface  of  the  vessel- wall, 
usually  on  a  vein,  but  sometimes  on  a  capillary,  a  small  but- 
ton-like elevation  or  hump,  which  little  by  little  grows  gradu- 
ally larger.  This  colorless  protuberance  is  seen  to  undergo 
manifold  variations  in  form,  to  throw  out  and  retract  little 
finger- like  processes;  it  finally  becomes  pear-shaped  with  its 
point  toward  the  vessel.  The  tapering  end  is  gradually  en- 
larged into  a  slender  pedicle,  which  finally  separates  from  the 
vessel-wall  and  is  retracted  into  the  body  of  the  leukocyte, 
for  this  separated  mass  of  protoplasm  is  now  readily  recog- 
nized as  such.  The  migration  of  a  leukocyte  takes  some- 
times two  hours.  The  same  process  is  repeated  at  a  large 
number  of  points  around  the  veins  and  capillaries,  so  that 
by  the  end  of  six  or  eight  hours  an  immense  number  of 
leukocytes  have  accumulated  along  the  external  surface  of  the 
vessel-walls.  In  the  arteries  this  phenomenon  is  not  noted. 


INFLAMMATION,  251 

It  does  occur  to  a  very  considerable  extent  in  the  capillaries, 
and  from  them  emigration  of  the  red  corpuscles  also  takes 
place.  The  leukocytes,  as  their  number  increases,  do  not  re- 
main in  the  neighborhood  of  the  vessels  from  which  they 
migrated ;  while  the  red  globules,  which  have  no  power  of 
amoeboid  movement,  remain  near  the  vessel  from  which  they 
escaped.  The  migration  of  the  leukocytes  continues  to  such 
an  extent  that,  as  there  is  no  room  for  them  in  the  interstices 
of  the  tissue,  some  reach  the  free  surface  of  the  mesentery. 
By  the  end  of  six  or  seven  hours  the  phenomenon  is  no  longer 
to  be  seen. 

The  serous  membrane  becomes  opaque,  due  to  an  exudate  of 
serum  from  the  bloodvessels,  which,  by  coagulating  and  en- 
tangling in  its  meshes  of  fibrin  white  and  red  blood-cells, 
forms  on  the  surface  of  the  mesentery  a  sort  of  a  pseudo- 
membrane. 

These  blood- vascular  changes  have  been  observed  in  warm- 
blooded animals ;  in  the  wing  of  a  bat  and  the  mesentery  of 
a  rabbit. 

The  dilatation  of  the  bloodvessels  was  supposed  by  Cohn- 
heim  to  be  due  to  the  direct  injury  of  the  vascular  walls  by 
the  trauma,  producing  chemical  and  molecular  changes  of  the 
greatest  importance.  These  changes  in  the  vascular  walls,  he 
suggested,  caused  an  increased  friction  of  the  blood  against 
the  walls,  which  was  supposed  to  explain  the  retardation  of 
the  current.  A  further  consequence  was  the  greatly  increased 
permeability  of  the  vessel-walls,  permitting  cellular  and  serous 
exudations.  We  cannot  state  with  certainty  the  exact  cause 
of  the  dilatation  of  the  vessels.  That  it  is  not  due  to  vaso- 
motor  paralysis  is  shown  by  the  fact  that  w7hen  inflamma- 
tion occurs  in  a  part  in  which  the  vaso-motor  nerves  have 
been  cut  the  vessels  still  further  dilate. 

The  slowing  of  the  current  is  an  important  factor  in  the  sub- 
sequent phenomena  of  margi nation  and  diapedesis.  This 
importance  has  been  experimentally  shown  by  the  fact  that 
artificial  acceleration  of  the  current  induced  by  the  intra- 
venous injection  of  a  6  per  cent,  salt  solution  materially  re- 
tards the  development  of  these  phenomena ;  and  directly  so 
in  proportion  to  the  degree  of  this  acceleration. 

An  increased  permeability  of  the  vessel  walls  has  been  ex- 


252     PATHOLOGY  OF  THE  BLOOD  AND  CIRCULATION. 

periraentally  demonstrated.  A  colloid  liquid  injected  into 
the  vessels  traverses  their  walls  even  under  feeble  pressure. 
The  microscope  fails  to  find  any  lesion,  though  it  is  claimed 
by  some  that  an  increase  in  the  size  of  the  natural  stomata 
between  the  endothelial  cells  can  be  made  out. 

Diapedesis :  The  demonstration  of  the  migration  of  leuko- 
cytes threw  a  flood  of  light  upon  a  very  important  question — 
the  source  of  inflammatory  cells.  The  formation  of  pus-cells 
from  connective-tissue  cells  had  never  been  seen  by  any  one. 
It  became  very  evident  that  at  least  the  great  majority  were 
migrated  leukocytes,  the  resemblance  of  which  to  the  cells 
crowding  all  inflammatory  tissues  had  been  commented  upon 
by  Virchow  and  other  observers  many  years  before.  It  is 
quite  probable  that  their  number  is  greatly  augmented  by  their 
multiplication  subsequent  to  migration.  As  an  explanation 
of  the  phenomena  of  diapedesis  two  theories  mainly  are 
invoked — the  theory  of  chemotaxis  and  the  theory  of  phago- 
cytosis. 

Chemotaxis :  It  has  been  known  for  a  number  of  years  that 
vegetable  plasmodia  are  attracted  by  certain  substances  and 
repelled  by  others :  if  placed  on  a  surface  at  a  little  dis- 
tance from  a  nutrient  material,  such  as  a  decoction  of  dead 
leaves,  the  organism  moves  toward  it ;  while  numerous  other 
materials,  such  as  a  solution  of  salt  and  sugar,  repel  it.  To 
these  phenomena  Stahl  gave  the  name  positive  and  negative 
trophotropism,  for  which  Pfefler  substituted  the  terms  positive 
and  negative  chemotaxis. 

A  similar  chemotactic  sensibility  has  been  demonstrated  on 
the  part  of  the  white  blood-cells  toward  various  substances. 

It  has  been  shown  that  whereas  some  materials,  such  as 
quinine,  alcohol,  chloroform,  repel  the  leukocytes,  cultures  of 
various  micro-organisms  and  proteid  substances  which  can  be 
separated  therefrom  attract  them.  So,  it  has  been  suggested, 
the  leukocytes  are  attracted  by  substances  formed  at  the  site 
of  inflammation. 

Phagocytosis  :  Metschnikoff,  studying  the  phenomena  of  in- 
flammation from  the  standpoint  of  a  biologist,  assigns  to  the 
leukocytes  the  main  role.  He  attempts  to  elucidate  these 
complex  phenomena  by  producing  them,  as  far  as  possible,  in 
organisms  of  the  most  simple  structure.  We  find  that  unicel- 


INFLAMMATION.  253 

lular  organisms  which  abound  in  media  surrounding  us  are 
subject  to  infectious  diseases.  Infection,  which  is  one  of  the 
most  important  causes  of  inflammation,  is  simply  a  struggle 
between  a  parasite  and  its  host.  We  must  regard  the  sum 
total  of  the  phenomena  of  inflammation  in  human  beings  as 
simply  the  efforts  of  nature  to  offset  the  effects  of  an  injury. 
However  simple  the  phenomena  resulting  from  similar  injury 
to  a  unicellular  organism — though  not  constituting  inflamma- 
tion as  we  are  clinically  familiar  with  it — yet  their  significance 
is  the  same,  and  represents  a  primitive  condition  of  this  proc- 
ess which  undergoes  a  slow  evolution  as  we  ascend  in  the 
animal  scale.  The  power  of  locomotion  and  intracellular 
digestion  is  the  amoeba's  mode  of  defence. 

Metschnikoff  says  :  "  If  we  take  a  specimen  (such  as  the 
yellow  plasmodium  of  Physarum)  on  our  object-glass  and 
touch  its  central  part  with  a  minute  glass  rod  previously 
heated  in  a  flame,  we  shall  produce  thermal  excitation.  Im- 
mediately after  being  touched  the  central  part  of  the  plas- 
modium dies  and  may  be  clearly  distinguished  from  the  living 
peripheral  portions,  which  remain  motionless  as  if  nothing 
has  occurred,  and  are  unaffected  by  the  necrosed  portion.  A 
few  hours  later,  however,  the  plasmodium  awakes  from  its 

passive  condition  and  creeps  away  from  the  dead  part 

We  thus  see  the  irritating  agencies  excite  in  the  plasmodium 
either  a  course  of  events  similar  to  those  which  accompany  the 
taking  of  solid  nutriment,  or  a  more  or  less  marked  repulsion. 
In  attempting  to  produce  a  reaction  which  should  correspond 
to  inflammation  in  the  higher  animals,  we  have  brought  about 
the  phenomena  of  attraction  or  repulsion  which  occur  so  fre- 
quently in  the  lives  of  plasmodia  and  the  inferior  animals 
generally/7 

In  embryo  sponges  there  are  stages  in  which  the  organism  is 
composed  of  but  two  layers,  the  inner  of  which  is  formed  of 
amoeboid  cells,  which  have  the  power  of  englobing  various 
solid  bodies  for  the  purpose  of  obtaining  nutriment  and  for 
defence. 

In  adult  sponges  there  are  three  layers — ectoderm,  mesoderm, 
and  entoderm,  and  now  the  function  of  digestion  devolves 
entirely  upon  the  entoderm,  and  the  amoeboid  cells  of  the 
mesodern  alone  possess  a  phagocytic  power. 


251     PATHOLOGY  OF  THE  BLOOD  AND   CIRCULATION. 

"It  is  apparent  that  the  inflammation  of  vertebrates,  in 
which  the  defending  phagocytes  emigrate  from  the  vessels  to 
proceed  against  offending  bodies,  is  distinguished  only  quanti- 
tatively from  the  analogous  phenomena  in  invertebrates,  and 
must,  therefore,  be  regarded  as  a  reaction  of  the  organism 
against  deleterious  agents.  We  must  conclude  that  the  essen- 
tial factor,  the  primum  movens  of  inflammation,  consists  in  a 
phagocytic  reaction  on  the  part  of  the  animal  organism.  All 
other  phenomena  are  merely  accessory,  and  may  be  regarded 
as  a  means  to  facilitate  the  access  of  phagocytes  to  the  injured 

part The  morbid  phenomena,  properly  speaking, 

such  as  the  primary  lesion  or  necrosis,  as  well  as  the  processes 
of  repair,  do  not  form  part  of  the  inflammation,  and  must  not 
be  confounded  with  it." 

Function  and  fate  of  the  cellular  exudate :  The  phagocytic 
power  of  leukocytes  is  well  recognized,  though  all  varieties 
do  not  possess  this  function  to  the  same  degree;  it  devolving 
mainly  upon  the  mononuclear  and  poly  nuclear  forms,  espe- 
cially the  neutrophiles.  The  lymphocytes  are  too  young  and 
have  too  little  extranuclear  protoplasm ;  nor  are  the  eosino- 
philes,  the  protoplasm  of  which  seems  to  be  undergoing  pos- 
sibly a  retrogressive  change,  ever  seen  to  englobe  red  blood- 
cells,  micro-organisms,  or  other  foreign  bodies.  Young  con- 
nective-tissue cells  —  fibroblasts  —  and  endothelial  cells  of 
bloodvessels  and  perhaps  of  lymphatics,  especially  when 
rapidly  proliferating,  possess  this  function  to  a  marked  de- 
gree. Giant-cells  are  also  occasionally  phagocytic. 

In  acute  inflammations  the  neutrophiles  are  the  most  active 
phagocytes,  while  in  chronic  inflammation  the  large  mono- 
nuclear  leukocytes  are  the  most  active.  Besides  this  function 
as  phagocytes  at  the  site  of  inflammation,  the  migrated  leuko- 
cytes undoubtedly  aid  in  the  restoration  of  the  tissue.  Ziegler 
has  long  maintained  that  they  develop  into  connective-tissue 
cells,  and  Metschnikoff  states  that  in  the  wounded  tail  of  a 
batrachian  tadpole,  if  watched  for  several  days,  he  has  seen 
the  polynuclear  cells  converted  by  fusion  of  their  nuclei  first 
into  mononuclear  cells  and  then  into  typical  branched  con- 
nective-tissue cells.  Also  in  rabbits  all  the  transitional  stages 
in  the  conversion  of  mononuclear  leukocytes  into  epithelioid 
and  giant-cells  have  been  noted. 


VARIATIONS  IN  THE  TYPE  OF  INFLAMMATION.   255 

The  function  of  the  serous  exudate  is  quite  probably  pri- 
marily nutritive.  Further,  it  frequently  possesses  bactericidal 
properties,  and  may  be  of  value  in  diluting  any  bacterial 
poison  present  at  the  site  of  inflammation.  On  the  other 
hand,  however,  the  serum  is  often  an  extremely  good  culture- 
medium  for  various  varieties  of  micro-organisms,  so  that  its 
presence  may  not  always  result  advantageously  to  the  tissue. 

Connective-tissue  changes : l  We  have  noted  that  in  addition 
to  their  phagocytic  function  the  migrated  leukocytes  are 
capable  of  playing  an  important  part  in  repair,  by  developing 
into  connective-tissue  elements;  and  further,  on  the  other 
hand,  that  young  connective-tissue  cells  and  endothelial  cells 
of  bloodvessels,  active  proliferative  changes  in  which  are 
always  noted  from  the  very  onset  of  all  inflammatory  processes, 
are  markedly  phagocytic,  though  this  certainly  cannot  be 
looked  upon  as  their  sole  function.  It  would  seem  that  these 
are  good  arguments  to  extend  our  conception  of  inflammation 
beyond  a  simple  phagocytic  reaction  on  the  part  of  the  animal 
organism.  There  are  examples  of  non-infectious  inflamma- 
tion where  the  leukocytic  migration  is  most  marked,  though 
not  necessarily  phagocytic  in  its  nature,  in  the  sense  in  which 
the  term  is  usually  employed. 

Synchronous  with  the  blood-vascular  alterations  at  the 
outset  of  inflammation,  to  which  are  always  added  more  or 
less  marked  degenerative  changes  in,  or  even  complete  destruc- 
tion of,  certain  of  the  cellular  elements  according  to  the 
severity  of  the  irritant,  active  proliferative  changes  in  the 
fixed  connective-tissue  cells  occur,  which  must  be  regarded 
as  a  restorative  as  well  as  a  defensive  manifestation,  and  hence 
should  be  included  in  our  conception  of  inflammation.  We 
conclude  that  inflammation  is  a  purposive  reaction,  having 
for  its  object  the  neutralization  of  the  effects  of  an  injury. 
In  this  sense,  then,  we  should  include  under  the  head  of  in- 
flammation the  phenomena  of  repair.  Undoubtedly  their 
significance  is  the  same ;  but  in  speaking  of  inflammation  we 
have  in  mind  a  well-defined  clinical  picture  which  here  is 
absent — the  only  difference  in  the  phenomena,  however,  being 
one  of  degree. 

Variations  in  the  type  of  inflammation:  In  every  inflamma- 

1  See  under  head  of  Repair, 


256     PATHOLOGY  Of1  THE  BLOOD  AND   CIRCULATION. 

tion  there  are  vascular  and  tissue  changes ;  but  there  is  a 
great  variability  in  the  character  of  inflammations  resulting 
from  differences  in  the  nature  of  the  irritants,  their  persist- 
ence, and  in  the  tissues  on  which  they  act. 

Irritants  may  be  divided  into  organized  and  unorganized, 
the  former  including  animal  and  vegetable  parasites,  and  the 
latter  mechanical,  physical,  and  chemical  influences.  The 
migrating  leukocytes  play  the  more  important  part  when  the 
irritant  is  organized.  There  is  a  very  considerable  difference 
between  a  blister  in  which  there  is  an  enormous  serous  exu- 
date  containing  but  few  leukocytes,  and  the  slight  serous  but 
enormous  cellular  exudate  produced  by  pyogenic  cocci. 

Though  this  property  of  inducing  the  migration  of  a  large 
number  of  leukocytes  is  well  recognized  as  belonging  to  cer- 
tain micro-organisms,  yet  the  various  other  factors  concerned 
in  bringing  about  such  a  result  are  not  fully  understood.  In- 
tense cold  produces  an  inflammation  which  is  accompanied  by 
an  excessive  migration  of  leukocytes,  while  the  inflammation 
produced  by  heat  is  accompanied  by  the  emigration  of  but 
very  few  leukocytes. 

Purulent  or  suppurative  inflammation  is  a  variety  character- 
ized by  an  excessive  migration  of  polymorphonuclear  leuko- 
cytes or  neutrophiles,  and  a  tendency  to  liquefaction  of  affected 
areas — i.  e.9  by  the  formation  of  pus. 

Pus  is  a  creamy  fluid,  of  specific  gravity  about  1030,  and 
usually  alkaline  in  reaction.  If  it  be  allowed  to  stand,  it 
separates  into  two  layers.  The  upper — the  liquor  puris — is 
a  clear  fluid,  yellowish  in  tint,  and  resembling  blood-serum. 
If  a  drop  from  the  opaque  lower  layer  be  examined  under 
the  microscope,  one  will  find  suspended  therein  a  great  num- 
ber of  colorless,  granular,  round  cells  (see  Fig.  98).  Their 
peculiar  horseshoe-shaped  nuclei  identify  them  as  polymor- 
phonuclear leukocytes.  If  the  specimen  is  from  an  acute 
abscess,  in  a  large  number  of  the  cells  amo?boid  movements 
may  be  noted,  especially  if  examined  on  a  warm  stage. 

A  circumscribed  collection  of  pus  in  any  tissue  is  known 
as  an  abscess.  In  addition  to  the  excessive  migration  of 
leukocytes  which  characterizes  purulent  inflammation,  there 
are  also  a  necrosis  and  liquefaction  of  the  tissue  at  a  given 
point,  setting  free,  as  it  were,  the  migrated  cells  within  this 


PURULENT  OR  SUPPURATIVE  INFLAMMATION.    257 

area.     In  other  words,  an  abscess  is  simply  a  liquefied  in- 
flammatory focus   containing   a   large   number  of  migrated 

FIG.  98. 


Pus  from  virulent  abscess-formation  (Grawitz).  The  leukocytes  show  marked  ne- 
crotic  changes,  chromolysis.  c,  c,  well-preserved  leukocytes;  EK,  connective- 
tissue  cells  from  the  neighboring  granulations  ;  z,  similar  cells  necrosed. 

leukocytes.     In  the  greater  number  of  cases  the  liquefaction 
of  the  tissues  is  a  sort  of  peptonization  brought  about  by  fer- 

FIG.  98J. 


Typhoid  ulcer  of  intestine,  second  week.  A,  mucosa  and  submucosa  \B,  muscularis ; 
C,  serous  coat ;  a,  villi ;  b,  slough,  on  both  sides  the  broad  infiltrated  border. 
X  12  (Schmaus). 

ments  the  product  of  bacterial  growth.  The  organisms  most 
frequently  concerned  in  purulent  inflammations  are  the  pyo- 
genic  staphylococci  and  streptococci,  though  the  bacillus 


17— Hist. 


258     PATHOLOGY  OF  THE  BLOOD  AND  CIRCULATION. 

coli,  gonococcus,  and  others  occasionally  prove  pyogenic. 
Around  the  central  fluid  mass,  the  pus,  there  is  first  a  layer 
which  is  soon  to  become  pus,  next  a  zone  of  inflammation  and 


FIG.  99. 


Parenchymatous  nephritis,  a,  cross-section  of  a  convoluted  tubule  of  the  kidney, 
the  lining  epithelium  of  which  is  the  seat  of  albuminoid  degeneration.  The 
cells  are  swollen  and  their  bodies  filled  with  abnormally  coarse  granules.  The 
cells  to  the  left  are  so  far  disintegrated  that  the  nuclei  'have  lost  most  of  their 
chromatin.  Such  cells  cannot  recover.  The  cells  to  the  right  are  less  pro- 
foundly altered  and  their  nuclei  retain  sufficient  chromatin  to  stain  slightly. 
These  cells  might,  perhnps,  recover.  Other  convoluted  tubules  similarly 
affected  are  represented  in  oblique  section,  b,  tubule  with  low,  unaffected 
epithelium,  the  nuclei  of  which  stain  deeply  ;  c,  round-cell  infiltration  of  the 
interstitial  tissue  in  the  neighborhood  of  a  Malpighian  body,  the  edge  of  which 
is  just  above  the  line  c.  Section  stained  with  hsematoxylin  and  eosin. 

repair,  and  then  healthy  tissue.     If  such    an   inflammatory 
process  occurs  on  the  skin  or  a  mucous  membrane,  the  result- 


REPAIR.  259 

ing  superficial  destruction  of  tissue  and  loss  of  substance 
constitute  an  ulcer  (see  Fig.  98J). 

Parenchymatous  and  interstitial  inflammation :  In  inflamma- 
tion of  glandular  structures,  in  some  instances,  the  degenera- 
tive or  proliferative  changes  in  the  epithelial  cells  may  be  the 
more  marked,  while  in  others  the  changes  in  the  interstitial 
tissue  are  the  more  pronounced,  suggesting  the  term  parenchy- 
matous  for  the  former  and  interstitial  inflammation  for  the 
latter  condition,  though  they  cannot  be  strictly  separated  from 
each  other  (see  Fig.  99).  The  same  terms  are  sometimes 
employed  in  a  somewhat  similar  manner  in  inflammations  of 
muscle  and  nerve-tissue. 

Productive  inflammation  (see  Fig.  100)  is  a  term  occasion- 
ally employed  when  the  proliferative  changes  predominate 
over  the  exudative  and  degenerative,  due  either  to  the  nature 
of  the  cause  or  the  extent  of  the  injury.  In  the  viscera,  when 
the  action  of  an  irritant  is  long  continued,  such  proliferative 
activity  of  the  connective-tissue  cells  may  lead  to  a  marked 
increase  in  the  sustentacular  tissue  and  a  secondary  atrophy 
of  the  parenchyma,  the  term  chronic  interstititial  inflammation 
being  applied  to  the  condition.  Productive  inflammation  is 
well  illustrated  in  the  process  of  repair. 

REPAIR. 

Healing  by  first  intention :  Immediate  reunion  of  an  aseptic 
wound  takes  place  with  scarcely  any  vascular  phenomena. 
The  prompt  juxtaposition  of  the  lips  of  the  wound  leaves  no 
opportunity  for  an  exudation  of  any  great  extent.  There  is 
more  or  less  hemorrhage,  a  small  amount  of  the  blood  coagu- 
lating between  the  edges  of  the  wound.  The  filaments  of 
fibrin  which  form  constitute  a  sort  of  scaffolding  between  the 
wounded  surfaces. 

By  the  end  of  twenty-four  hours  there  is  evidence  of  a 
superactivity  on  the  part  of  the  injured  connective-tissue  cells. 
They  become  hypertrophied,  their  divided  prolongations 
grow  and  new  ones  are  protruded,  extending  along  the  fibrin 
scaffolding,  uniting  with  similar  prolongations  from  other  cells, 
and  thus  forming  a  second  scaffolding  firmer  than  the  first. 
The  cells  then  complete  the  formation  of  the  cicatrix  by  the 


260    PATHOLOGY  OF  THE  BLOOD  AND  CIRCULATION. 

development  of  white  fibrous  and  yellow  elastic  fasciculi. 
Though  the  migration  of  leukocytes  may  have  been  a  little 
exaggerated,  they  have  taken  no  active  part  in  the  reparative 
process. 

We  might  say  that  the  phenomena  of  inflammation  have 
been  reduced  to  their  simplest  terms — complete  or  partial 
destruction  of  some  cells,  and  a  marked  functional  super- 


Chronic  interstitial  myocarditis,  late  stage,  a,  dense  fibrous  tissue,  the  final  result 
of  the  interstitial  inflammation;  b,  b'-,  b",  atrophied  cardiac  muscle-cells; 
6',  vacuolation  of  a  less  atrophic  cell ;  b",  section  showing  anastomotic  branch 
joining  two  cells ;  c,  partially  obliterated  bloodvessels. 

activity  of  other  connective-tissue  elements  having  for  its 
object  the  complete  restoration  of  the  injured  part. 

When  the  irritant  is  greater  the  reparative  process  pro- 
gresses with  greater  energy. 

Healing  by  second  intention  :  When  the  surfaces  of  a  wound 
are  not  in  apposition  or  are  septic — i.  c.,  infected  by  bacteria — 
the  reactionary  and  reparative  phenomena  progress  with 
greater  energy  because  of  the  greater  call  upon  the  reparative 
efforts  of  the  organism,  or  the  greater  severity  of  the  irritant. 


HEALING  BY  SECOND  INTENTION. 


261 


The  wound  is  said  to  heal  by  second  intention,  and  with  pus- 
formation  if  it  is  septic.     It  is  a  much  slower  process,  either 


FIG.  101. 


Healing  of  an  incised  wound  of  the  skin  united  by  suture,  sixth  day.  a,  epider- 
mis ;  6,  corium;  c,  fibrinous,  d ,  hemorrhagic  exudate;  d,  newly  formed  epithe- 
lium, containing  numerous  karyokinetic  figures  and  showing  epithelial  plug 
projecting  into  exudate  lying  beneath ;  e,  karyokinetic  figures  at  some  distance 
from  line  of  incision ;  /,  new  connective  tissue  growing  from  connective-tissue 
spaces  and  containing  cells  with  karyokinetic  figures  and  bloodvessels  with 
growing  walls  ;  g,  growing  new  connective  tissue  with  leukocytes  ;  h,  collection 
of  leukocytes  at  the  lower  angle  of  the  wound :  i,  fibrinoblasts  lying  inside  the 
exudate ;  k,  sebaceous  gland  ;  I,  sweat-gland.  X  80  (Ziegler). 

because  the  wound  must  heal  in  from  the  sides  and  bottom  or 
because  tissue-destruction  is  greater  by  reason  of  the  injurious 


262    PATHOLOGY  OF  THE  BLOOD  AND  CIRCULATION. 

effects   of    highly   noxious    chemical   products   of    bacterial 
growth  on  the  new  proliferating  cells. 

If  we  examine  an  open  wound — i.  e.,  one  which  is  healing 
by  second  intention — it  will  be  noted  that  its  surface  is  covered 
by  papillary  elevations  about  the  size  of  pin-points.  This 
is  the  type  of  tissue  concerned  in  the  repair  of  all  such  lesions, 
and  on  account  of  its  appearance  is  called  : 


FIG.  102. 


a 


Phagocytes  from  granulations  infected  with  virulent  anthrax  bacilli  (Afanassieff). 
a,  thread  of  bacilli,  partly  within  and  partly  outside  of  a  phagocyte  ;  both  por- 
tions show  a  vacuolation  of  the  bacilli,  indicative  of  their  degeneration,  d, 
thread  almost  entirely  incorporated.  Within  the  cell  the  incorporated  bacilli 
lie  in  vacuoles  in  the  cytoplasm,  probably  digestive  vacuoles.  In  b  and  e  simi- 
lar appearances  are  presented,  c,  degenerating  thread  of  bacilli  from  the  fluid 
of  the  granulations.  Vacuolation  has  also  taken  place  in  this  thread, 
showing  that  the  fluids  of  the  granulations  have  a  destructive  influence  upon 
the  bacilli. 

Granulation-tissue :  On  microscopical  examination  one  finds 
these  little  elevations  to  be  composed  of  loops  of  newly  formed 
bloodvessels  (see  Fig.  101)  surmounted  by  a  mass  of  rapidly 
proliferating  connective-tissue  cells  and  migrated  leukocytes. 
In  addition  there  may  be  present  certain  larger  cellular  ele- 
ments. One  variety,  the  giant-cell,  is  often  many  times  the 
size  of  a  leukocyte,  its  chief  characteristic  being  a  variable 
number  of  nuclei — sometimes  as  many  as  one  hundred, 
usually,  however,  from  five  to  twenty — irregularly  arranged, 
sometimes  around  the  periphery  of  the  cell,  evenly  distributed 


GRANULA  TION-TISSUE. 


263 


through  the  cell-protoplasm  or  clustered  in  one  spot.  These 
cells  are  markedly  phagocytic,  englobing  and  removing 
bacteria,  fragments  of  the  red  blood-corpuscles  and  proto- 
plasmic debris  generally  (see  Figs.  102  and  103).  Another 
variety  is  large  and  fusiform  with  an  elongated  nucleus. 

In  the  midst  of  these  innumerable  cellular  elements  run 
newly  formed  capillary  bloodvessels,  the  walls  of  which  are 
formed  of  a  single  layer  of  cells  scarcely  differentiated  from 
those  surrounding.  The  exact  method  of  the  formation  of 
these  new  bloodvessels  is  as  yet  obscure. 

As  the  reparative  process  progresses  the  young  spherical 
connective-tissue  cells  become  more  angular  and  later  fusiform. 
As  they  often  resemble  the  epithelial  cells  of  mucous  mem- 

FIG.  103. 


Phagocytes  from  aseptic  granulations  (Nikiforoff ).  C,  phagocytes  with  pseudopodia ; 
E,  without  pseudopodia;  F,  proliferating,  the  daughter-nuclei  in  the  spirem 
phase  of  karyokinesis  ;  A,  B.  D,  with  leukocytes,  fragments  of  tissue,  and  red 
corpuscles  in  their  cytoplasm. 

branes  they  are  sometimes  called  epithelioid.  To  these  cells, 
which  are  especially  consecrated  to  the  restoration  of  connec- 
tive tissue,  Ziegler  applies  the  term  fibroblasts;  or  chondro- 
blasts  or  osteoblasts  if  concerned  in  the  regeneration  of 
cartilage  or  bone.  Still  further  changes  in  shape  take  place, 
until  finally  they  become  fully  developed  flat  and  slender 
connective-tissue  cells. 

Having    thus    rapidly   attained    their    full   development, 


264     PATHOLOGY  OF  THE  BLOOD  AND  CIRCULATION. 

evidences  of  advancing  senile  degeneration  manifest  them- 
selves with  equal  rapidity,  the  numerous  new  bloodvessels 
undergoing  atrophy  in  a  similar  manner,  and  thus  is  formed 
the  cicatrix. 

The  formation  of  new  fibrous  tissue  and  regeneration  of 
other  connective  tissues  occur  in  much  the  same  manner, 
their  differentiation  occurring  secondarily. 

THE  INFECTIVE  GRANULOMATA. 

Under  this  head  are  usually  described  a  number  of  infec- 
tious diseases  all  characterized  by  the  formation  of  tumor-like 
nodular  masses,  microscopically  somewhat  resembling  granu- 
lation-tissue in  the  number  and  character  of  their  cells,  which 
have,  however,  but  little  tendency  to  develop  into  a  perma- 
nent tissue,  and  are  very  liable  to  undergo  degenerative 
changes.  They  are  forms  of  subacute  inflammation. 

Tuberculosis. 

The  term  tubercle  was  at  one  time  applied  to  any  nodular 
growth.  By  Laennec  it  was  employed  mainly  in  connection 
with  the  large  caseous  yellow  nodules  observed  in  phthisical 
lungs.  Baillie  (1794)  was  the  first  to  call  attention  to  the 
small,  gray,  millet-seed-sized  tubercles  found  in  the  lungs,  and 
which  are  now  regarded  as  the  anatomical  basis  of  the  larger 
yellow  nodules.  But  even  the  smallest  "  miliary  tubercle " 
is  found  microscopically  to  be  made  up  of  still  smaller  cellular 
tubercles. 

Though  the  histology  of  these  cellular  tubercles  is  quite 
distinctive,  since  the  discovery  of  the  specific  microbic  cause 
by  Koch  in  1882,  the  presence  of  this  bacillus  must  be  re- 
garded as  the  essential  characteristic  of  the  disease  :  this  then 
is  the  criterion,  whatever  the  macroscopic  or  microscopic 
character  of  the  lesion  (see  Figs.  104,  105). 

Histological  tubercle  :  The  first  effect  of  the  presence  of  the 
tubercle  bacillus  in  a  tissue  is  the  multiplication  of  its  fixed 
connective-tissue  cells,  resulting  in  the  formation  of  cells 
termed  epithelioid  on  account  of  the  resemblance  to  epithelial 
cells  in  their  abundance  of  protoplasm.  There  is  also 


TUBERCULOSIS.  265 

excited  a  migration  of  leukocytes,  and  surrounding  the  epi- 


FIG.  105. 


FIG.  104. 


Tubercle  bacilli  in  giant-cell  (from  tuber-       Tubercle  bacilli  (from  a  colony  on 
culosis  of  horse).    X  600  (Cheyne).  blood-serum),  showing  the  wavy 

parallel  lines.  X  500  (after  Koch). 

FIG.  106. 


A  tubercle  from  a  case  of  tuberculosis  of  the  liver.  A  multinucleated  giant-cell 
occupies  the  centre.  Around  is  an  area  of  commencing  caseation  and  outside 
this  a  zone  consisting  principally  of  fibroblasts,  and,  to  a  less  extent,  of  leuko- 
cytes. The  leukocytes  are  most  numerous  on  the  side  where  caseation  is 
most  advanced.  X  250. 

thelioid  cells  we  find  a  layer  of  smaller  lymphoid  cells,  both 
often    being    supported   by  a  fine   connective-tissue    reticu- 


266     PATHOLOGY  OF  THE  BLOOD  AND  CIRCULATION. 

him.  Such  an  arrangement  of  epithelioid  and  lymphoid 
cells,  with  often  a  large  multi  nucleated  giant-cell  in  their 
centre,  constitutes  the  typical  histological  tubercle  (see  Fig. 
106). 

The  structure  of  these  tubercles,  however,  varies  consider- 
ably ;  in  some  instances  the  leukocytic  migration  is  so  great 
as  almost  to  hide  the  epithelioid  cells.  If  properly  stained,  the 
tubercle  bacillus  may  be  found  between  the  epithelioid  cells 
first  formed ;  later  they  are  more  numerous,  many  being 
within  the  cells,  especially-  within  the  giant-cells. 

The  giant-cell  was  at  one  time  supposed  to  be  typical  of 
tuberculosis,  but  it  is  now  known  to  be  frequently  found  in 
other  chronic  inflammatory  processes,  and  in  some  tumor- 
formations,  though  neither  so  abundant  nor  so  conspicuous. 
They  often  have  as  many  as  fifteen  to  twenty  nuclei  arranged' 
around  the  periphery  of  the  cell  or  at  either  of  its  poles.  By 
some  observers  the  giant-cells  are  supposed  to  result  from 
the  rapid  multiplication  of  the  nuclei  of  the  epithelioid  cells 
without  division  of  the  cell-protoplasm  ;  according  to  Metsch- 
nikoif  and  others,  they  result  from  the  running  together  of 
the  phagocytic  leukocytes  and  epithelioid  cells,  combining,  as 
it  were,  for  a  common  weal. 

Caseation  is  a  most  characteristic  change  affecting  the  tuber- 
cle. It  consists  in  the  transformation  of  its  centre,  often,  in 
fact,  of  the  whole  tubercle  — depending  on  the  abundance  and 
virulence  of  the  bacteria — into  a  structureless,  opaque,  and 
granular  material,  macroscopically  resembling  cheese.  In 
part  this  is  due  to  toxins  resulting  from  the  growth  of  the 
tubercle  bacilli ;  and  in  part  is  due  to  the  entire  absence  of 
blood-supply,  which  can  be  demonstrated  in  properly  injected 
specimens,  the  capillaries  being  traceable  to  the  margin  of  the 
tubercle  only. 

Fibroid  transformation  :  When  the  inflammatory  process  is 
very  chronic,  and  the  bacilli  few  in  number,  in  place  of  a 
necrotic  and  destructive  process — caseation — the  tissues  seem 
to  gain  the  upper  hand,  and  by  the  active  proliferation  and 
development  of  the  connective-tissue  cells  a  new  fibrous  tissue 
is  formed  and  thus  the  disease  is  limited ;  the  tubercle  is  said 
to  have  undergone  a  fibroid  change,  and  is  replaced  by  scar- 
tissue. 


FEVER. 


267 


FIG.  107. 


Syphilis. 

The  lesion  which  places  syphilis  among  the  infective  granu- 
lomata  is  the  gumma,  which  occurs  in  the  late  or  tertiary  stage 
of  the  disease. 

Though  the  cause  of  the  disease  is  not  definitely  determined, 
no  one  doubts  the  living  nature  of  the  contagium. 

The  gumma  occurs  in  almost  all  the  tissues  of  the  body, 
most  frequently,  however,  in  the  skin  and  subcutaneous  cellu- 
lar tissue ;  in  bone  (tibia,  sternum,  and  skull) ;  in  the  brain 
and  its  membranes  (less  frequently  in  the  spinal  cord) ;  and  in 
the  liver,  kidneys,  and  lungs.  It  presents  as  a  firm  yellowish 
white  nodular  mass  varying  in  size  from  that  of  a  hemp-seed 
to  that  of  an  apple.  On  section  it 
has  a  gelatinous  or  gummy  appear- 
ance. The  centre  is  often  yellow 
and  cheesy  from  the  necrosis  it  is 
prone  to  undergo.  If  the  nodule 
is  superficially  situated,  this  necrotic 
softening  frequently  results  in  the 
formation  of  deep  excavated  ulcers. 

Microscopically  the  gumma  is 
composed  of  migrated  leukocytes 
and  proliferating  connective-tissue 
cells  of  various  forms.  Epithelioid 
and  giant-cells  are  less  frequently 
seen  than  in  tuberculosis.  If  casea- 
tion  has  begun,  in  the  centre  is 
found  an  opaque,  homogeneous,  and 
granular  material.  At  the  periphery  there  is  a  vascular 
newly-forming  connective  tissue  (Fig.  107). 

Leprosy,  glanders,  actinomycosis,  and  rhinoscleroma  are  also 
characterized  by  the  formation  of  nodular  masses  of  granula- 
tion-like tissue. 

FEVER. 

Accompanying  inflammation  there  is  often  very  consider- 
able constitutional  disturbance.  The  body-temperature  may 
be  elevated ;  the  pulse  and  respirations  accelerated ;  glandular 
secretions,  altered  ;  metabolism  disturbed  ;  definite  anatomical 


Gummy  growth  from  liver,  a, 
central  portions  of  growth, 
consisting  of  granular  debris ; 
6,  peripheral  granulation-tis- 
sue ;  r,  a  bloodvessel.  X  100 
(Cornil  and  Ranvier). 


268     PATHOLOGY   OF  THE  BLOOD   AND   PECULATION. 

changes  in  various  tissues  likewise  accompanying  these  phe- 
nomena— all  of  which  are  included  in  the  clinical  term  fever. 

Rise  of  body-temperature  is  the  most  essential  phenomenon 
to  the  existence  of  fever. 

The  normal  constant  temperature  of  the  body  depends  on 
an  equilibrium  between  the  processes  of  heat-production  and 
heat-dissipation,  which  is  maintained  through  the  influence 
of  the  nervous  system  ;  the  exact  nature  of  this  mechanism, 
however,  is  not  yet  fully  understood.  In  fever  this  equilib- 
rium is  disturbed,  so  that  the  processes  of  heat-dissipation 
and  heat-production  do  not  bear  a  normal  relation  to  each 
other. 

Etiology :  Clinically  fever  has  been  observed  to  follow  con- 
siderable extravasations  of  blood ;  experimentally  it  occurs 
after  transfusion  of  blood  from  one  animal  to  another  and 
also  after  intraperitoneal  injections  of  blood. 

The  demonstration  of  the  fibrin-ferment  as  the  pyogenic 
substance  capable  of  exciting  such  a  rise  of  temperature 
suggested  the  investigation  of  other  ferments,  and  it  was 
found  that  the  intravenous  injection  of  pepsin,  trypsin,  and 
papoid  produced  a  well-defined  fever.  This  type  of  fever 
corresponds  to  that  observed  by  surgeons  after  extensive 
aseptic  wounds,  as  a  subcutaneous  fracture,  the  pyogenic 
material  resulting  from  the  disintegration  of  the  injured 
tissues. 

Most  morbid  processes  with  which  fever  is  associated  are 
due  to  micro-organisms,  and  it  is  consequently  quite  natural  to 
turn  to  these  elementary  forms  of  vegetable  life  in  endeavor- 
ing to  elucidate  this  subject.  Early  investigators,  less  than 
fifty  years  ago,  demonstrated  that  injections  of  putrefactive 
materials  into  the  blood  of  animals  were  capable  of  producing 
marked  febrile  reactions,  and  a  knowledge  of  the  part  played 
by  micro-organisms  in  the  production  of  putrefaction  made 
quite  evident  the  importance  of  their  rdle  in  fever. 

In  1863  Davaine  described  a  rod- shaped  organism  in  the 
blood  of  animals  sick  with  splenic  fever,  and  found  that  in  a 
healthy  animal,  if  inoculated  with  the  blood  of  an  animal  so 
affected,  the  disease  was  reproduced.  Subsequently  Pasteur 
showed  that  if  these  organisms  were  removed  by  filtration 
through  earthen  cylinders,  though  the  disease  could  not  then 


THE  CIRCULATORY  APPARATUS.  269 

be  reproduced  by  inoculation,  there  resulted  a  febrile  reaction, 
which  could  only  be  attributed  to  chemical  poisons — called 
ptomains  or  toxins — the  result  of  the  growth  of  the  bacteria. 

These  chemical  substances  may  be  the  product  of  organisms 
which  are  not  capable  of  existing  in  the  living  body,  but  only 
in  dead  vegetable  or  animal  tissues — i.  e.,  saprophytic  bacteria, 
to  which  class  belong  the  poisonous  alkaloids  which  have 
been  isolated  from  putrefying  fish,  meat,  sausage,  cheese,  etc. 
But  of  far  greater  clinical  importance  in  the  etiology  of 
fever  are  the  products  of  pathogenic  bacteria. 

Undoubtedly  febrile  rise  of  temperature  may  be  produced 
by  other  agencies,  such  as  fear  and  affections  of  the  nervous 
system ;  but  here  grave  functional  and  anatomical  disturb- 
ances are  entirely  absent. 

The  significance  of  fever  is  not  known,  though  modern  ex- 
perimental evidence  supports  the  theory  that  it  is  a  conserva- 
tive effort  on  the  part  of  nature  to  combat  the  noxious  sub- 
stances which  give  rise  to  it.  In  animals  rendered  hyperther- 
mic  by  external  heat  or  cerebral  puncture  and  inoculated  with 
various  organisms — pneumococcus  and  others — the  increase 
in  body-temperature  seemed  to  exert  a  most  favorable  influ- 
ence on  the  course  of  the  infection. 

The  anatomical  changes  in  fever,  due  to  the  increased  tem- 
perature alone,  are  few.  It  is  difficult  to  separate  the  results 
produced  by  the  high  temperature  from  those  produced  by  its 
exciting  cause.  Cloudy  swelling  and  fatty  degeneration  of  the 
heart,  liver,  and  kidneys,  are  probably  in  part  due  to  the  fever 
itself,  though  in  part  undoubtedly  to  toxic  substances  circu- 
lating in  the  blood. 

THE  CIRCULATORY  APPARATUS. 

Hyperaemia  is  an  increase  in  the  amount  of  blood  in  a  part : 
and  is  either  actual,  due  to  an  increase  of  the  flow  to  the 
part ;  or  passive,  due  to  an  obstruction  of  the  outflow. 

Active  hyperaBmia :  Blushing  is  a  physiological  example. 
Pathologically  it  is  hardly  met  except  associated  with  some  of 
the  phenomena  characteristic  of  inflammation.  A  variety 
due  to  vaso-motor  paralysis,  as  seen  in  experimental  section  of 
the  cervical  sympathetic  in  animals,  is  occasionally  met  with 
clinically,  as  after  gunshot-wound  of  the  same  nerve. 


270     PATHOLOGY  OF  THE  BLOOD  AND   CIRCULATION. 

Passive  hypersemia  is  produced  locally  by  thickening  of 
venous  walls,  external  pressure  on  the  veins  of  a  part  by  a 
tumor,  gravid  uterus,  etc.  Cardiac  weakness  produces  a  gene- 
ral venous  congestion  finally,  if  severe  enough,  of  all  the  tis- 
sues of  the  body. 

The  consequences  of  venous  congestion  are  more  important 
than  those  of  active  congestion — the  blood-serum  transudes  in 
greater  quantities  than  can  be  removed  by  the  lymphatics,  and 
the  tissues  become  cedematous  and  swollen.  In  the  internal 
organs  there  may  result  pressure-atrophy  of  the  true  paren- 
chyma-cells and  an  increase  of  the  connective-tissue  elements. 

FIG.  108. 


Section  of  white  thrombus  containing  few  leukocytes,  a,  granular  masses ;  &,  granu- 
lar threads  of  fibrin  arranged  in  a  network  ;  c.  parallel  arranged  threads  of  fibrin. 
X  200  (Zeigler). 

Local  anaemia  or  ischaemia  :  This  occurs  where  there  is  inter- 
ference with  the  blood-supply  of  a  tissue,  and  results  in  atrophy 
or  some  degenerative  change,  or  if  long  continued  in  necrosis. 
It  is  produced  by  thrombosis  or  embolism,  atheroma  of  the 
vessel-walls,  arterial  spasm,  or  external  pressure. 

Thrombosis  is  the  coagulation  of  blood  within  the  heart  or 
bloodvessels  during  life. 

The  appearance  and  structure  of  a  thrombus  depend  on  the 
rapidity  with  which  it  is  formed ;  if  slowly,  it  is  composed  of 


EMBOLISM.  271 

layers  of  fibrin  containing  blood- plates  and  leukocytes  in  its 
meshes  and  is  of  a  grayish-white  color  ;  if  rapidly,  as  the  result 
of  the  almost  complete  stoppage  of  the  circulation,  it  is  com- 
posed of  fibrin  and  all  the  elements  of  the  blood,  is  soft  and 
red,  resembling  a  post-mortem  clot  (Fig.  108). 

The  cause  of  thrombosis  is  found  either  in  alterations  in 
structure  of  the  vessel-walls,  in  the  composition  of  the  blood 
or  the  rapidity  of  its  flow.  If  the  circulation  is  arrested 
at  any  point,  coagulation  ensues  as  the  result  of  the  altered 
nutrition  of  the  vessel-wall,  producing  structural  changes 
incompatible  with  preservation  of  the  normal  fluidity  of  the 
blood.  Inflammatory  and  degenerative  changes  in  the  vas- 
cular walls,  as  well  as  alterations  in  the  composition  of  the 
blood,  for  instance  after  a  prolonged  illness  like  typhoid  fever, 
favor  the  same  result. 

The  fate  of  a  thrombus  may  be  organization,  calcification 
forming  phleboliths,  or  fatty  degeneration  and  liquefaction. 

Embolism  is  the  process  of  plugging  or  stopping  up  of  a 
bloodvessel  by  foreign  bodies  of  various  description,  carried 
in  the  blood-stream  and  too  large  to  pass  through  the  vessel 
at  that  point. 

The  plug  or  embolus  may  be  a  portion  of  a  thrombus ;  of 
a  diseased  heart-valve  or  of  a  tumor;  masses  of  bacteria 
and  other  parasites,  and  also  pigment,  as  in  malaria  ;  parti- 
cles of  fat ;  and  in  wounds  of  large  veins,  air,  which  may 
have  gained  entrance  (Fig.  109).  Its  point  of  lodgement 
depends  on  its  source ;  if  from  the  systemic  veins,  it  will  be 
arrested  by  branches  of  the  pulmonary  artery  ;  if  from  the 
pulmonary  veins  or  left  side  of  heart,  it  will  occlude  some 
systemic  artery,  most  frequently  in  the  spleen,  kidneys,  or 
brain ;  if  from  tributaries  of  the  portal  vein,  it  will  be 
arrested  by  branches  of  that  vein  within  the  liver.  If  the 
obstructed  artery  is  terminal — i.  e.,  has  no  free  anastomoses — 
an  infarct  is  the  result. 

Infarcts  may  be  anemic  or  hemorrhagic.  The  circulation 
beyond  the  embolus  is  arrested — a  wedge-shaped  anaemic  area 
is  produced  in  which  later  occur  coagulative  necrosis  and 
caseation,  the  degenerated  tissue  being  finally  absorbed. 

In  some  cases,  however,  the  affected  wedge-shaped  area  is 


272     PATHOLOGY  OF  THE  BLOOD  AND   CIRCULATION. 

engorged  with  extravasated  blood  supposed  possibly  to  be 
due  to  a  back  flow  from  the  veins,  in  which  case  the  final 
remaining  scar  is  pigmented  (Fig.  110). 

(Edema:  Normally  a  certain  amount  of  fluid  transudes 
from  the  capillary  bloodvessels  into  the  interstices  of  con- 
nective tissues  and  the  various  serous  cavities  of  the  body ; 
when  the  amount  of  this  fluid  is  increased  or  its  removal  by 


FIG.  109. 


A  thrombus  in  the  saphenous  vein, 
showing  the  projection  of  the 
conical  end  of  the  thrombus  into 
the  femoral  vessel.  S,  saphenous 
vein;  T,  thrombus;  C,  conical 
end  projecting  into  femoral  vein. 
At  v,  v,  opposite  the  valves,  the 
thrombus  is  softened  (Virchow). 


Diagram  of  a  hemorrhagic  infarct.  a,  artery 
obliterated  by  an  embolus  (e) ;  v,  vein  filled 
with  a  secondary  thrombus  (th);  I,  centre 
of  infarct  which  is  becoming  disintegrated  ; 
2,  area  of  extravasation ;  3.  area  of  col- 
lateral hypersemia  (O.  Weber). 


the  veins  and  lymphatics  is  lessened  the  condition  is  known 
as  oedema  or  dropsy.  The  increased  transudation  may  be 
caused  by  arterial  or  venous  hypersemia,  hydrsemic  states  of 
the  blood,  and  possibly  by  alterations  in  the  walls  of  the 
bloodvessels. 

Obstruction  of  the  lymphatic  circulation  is  never  a  power- 
ful factor  in  the  production  of  dropsy  ;  but  venous  obstruction 
is  a  most  important  mechanical  cause. 

Clinically  the  chief  varieties  of  cedema  are  cardiac,  renal, 
cachectic,  and  angioneurotic.  Cardiac  dropsy  is  an  example 
of  increased  transudation  from  passive  hypersemia,  due  to  the 


(EDEMA.  273 

inability  of  the  heart  to  maintain  the  normal  force  of  the  cir- 
culation. Renal  dropsy  results  from  alterations  in  the  blood 
as  a  consequence  of  its  loss  of  albumin  and  possibly  also 
from  degenerative  changes  in  the  vascular  walls.  Cachectic 
oedema  is  associated  with  almost  any  condition  of  impaired 
health  accompanied  by  anaemia.  Localized  cedemas  are  some- 
times associated  with  lesions  of  the  nervous  system,  as  those 
attending  neuritis,  neuralgia,  and  occasionally  hemiplegia. 

18-Hist. 


CHAPTER    II. 

PATHOLOGY   OF  NUTRITION. 

ALL  pathological  processes  are  primarily  nutritive ;  but 
the  term  is  usually  restricted  to  necrosis,  the  degenerations 
and  infiltrations,  hypertrophy,  atrophy,  and  tumors. 

Local  Death. 

Necrosis  is  a  local  death  of  simple  cells  or  groups  of  cells, 
in  contradistinction  to  general  or  somatic  death.  It  is  due  to 
mechanical,  chemical,  and  thermic  injuries ;  interference  with 
the  blood-supply ;  and  to  lesions  of  the  central  nervous  sys- 
tem— i.  e.,  trophic  disturbances. 

The  mechanical  causes  of  necrosis  are  numerous,  such  as 
the  crushing  of  a  finger  by  violence.  External  pressure,  as 
from  bandages  or  splints  on  bony  prominences,  may  cause 
necrosis,  as  may  also  tension,  or  pressure  from  within,  pro- 
duced by  inflammatory  exudates.  It  is  often  difficult  to  dis- 
tinguish between  the  direct  injurious  effect  of  mechanical, 
chemical,  or  thermic  trauma  on  the  tissue-cells  and  their 
indirect  effect  through  circulatory  disturbances,  as  the  blood 
also  undergoes  changes  resulting  in  coagulation  and  stasis  in 
the  capillaries.  A  temperature  of  50°  to  68°  C.,  if  continued 
for  any  length  of  time,  causes  necrosis  and  higher  temperatures 
more  quickly. 

Obstruction  of  the  circulation  by  a  thrombus,  embolus,  or 
atheroma  of  the  vessel-walls  produces  necrosis.  A  number  of 
these  causes  may  act  together.  If  the  vitality  of  a  tissue  has 
been  reduced  by  long-continued  passive  hypersemia,  for  exam- 
ple as  the  result  of  uncompensated  valvular  disease  of  the  heart, 
it  succumbs  much  more  rapidly.  A  slight  injury  may  suffice 
in  the  aged  or  in  conditions  like  typhoid  fever,  where  the  vital 
forces  are  greatly  depressed.  In  senile  gangrene,  to  the 
lowered  vitality  of  the  tissue  are  added  a  weak  heart  and 
274 


NECROSIS. 


275 


atheromatous  vessels.  In  the  so-called  neuropathic  necroses 
occurring  in  diseases  of  the  nervous  system  an  important  part 
is  undoubtedly  played  by  trauma  and  circulatory  disturbances. 
Under  the  microscope  it  is  noted  that  the  cell-nucleus  loses 
its  affinity  for  nuclear  dyes — "  chromolysis" — or  the  chroma- 
toplastic  substances  are  broken  up  into  fragments — "  karyo- 
lysis" — and  the  nucleus  finally  disintegrates  and  disappears,  the 
cell-protoplasm  becoming  homogeneous  in  appearance.  There 

FIG.  111. 


Fat-necrosis.  The  abrupt  transition  from  the  healthy  cells  on  the  left  to  the  ne- 
crosed cells  on  the  right  is  well  marked.  The  contents  of  the  affected  cells  are 
finely  granular.  (From  a  specimen  by  Dr.  Rolleston.) 

is  always  more  or  less  inflammatory  reaction  in  the  surround- 
ing tissues.  Complete  regeneration  or  cicatrization,  calcifica- 
tion, or  cystic  formation  may  follow. 

Several  varieties  of  necrosis  are  usually  described  :  Coagala- 
tion-necrosis  is  a  variety  in  which  there  is  coagulation  of  the 
fluids  normally  present — lymph — or  of  inflammatory  exudates, 
and  the  cellular  protoplasm  of  the  tissue.  Fibrin  is  deposited 
in  the  form  of  granules  or  fine  fibrillae  ;  the  cells  lose  their 
nuclei  and  their  protoplasm  becomes  granular.  The  necessary 
ferment  to  produce  this  coagulation  is  derived  either  from  the 
degenerating  and  disintegrating  cells  or  from  bacterial  prod- 


276  PATHOLOGY  OF  NUTRITION. 

ucts.  Macroscopieally  the  affected  area  is  pale,  opaque,  waxy, 
and,  later,  gray  in  appearance.  On  mucous  surfaces  a  false 
membrane  is  formed,  as  seen  in  diphtheria. 

In  liquefaction-necrosis  there  is  a  kind  of  peptonization  of 
the  tissue-elements,  which  break  down  and  become  fluid,  the 
active  agent  being  some  bacterial  or  non-bacterial  ferment. 

The  term  caseation  is  used  to  describe  a  degenerative  change 
where  the  tissue  macroscopically  has  the  appearance  of  hard 
or  soft  cheese,  and  is  most  frequently  seen  in  connection  with 
tubercular  and  syphilitic  inflammations.  Microscopically  one 
finds  simply  a  fine  granular  debris. 

Fat-necrosis  is  a  variety  which  affects  fatty  connective 
tissues.  It  is  most  frequently  noted  in  the  abdominal  cavity 
in  the  subperitoneal  fat,  and  generally  is  associated  with 
some  pathological  change  in  the  pancreas.  It  is  character- 
ized by  the  formation  of  opaque,  white  areas  about  the  size 
of  a  pea.  Microscopically  the  cell-contents  are  crystalline, 
opaque,  or  granular  (Fig.  111). 

Gangrene  is  the  death  of  tissue  en  masse.  There  are  two 
varieties,  dry  or  mummification  and  moist  or  sphacelus.  The 
former  occurs  when  the  part  is  so  situated  that  rapid  evapora- 
tion of  the  fluids  present  takes  place,  especially  when  the 
necrosis  has  been  caused  by  interference  with  the  blood-supply. 
The  latter  occurs  where  evaporation  is  hindered  and  where 
the  blood  reaching  the  part  cannot  escape  owing  to  venous 
obstruction.  The  presence  of  moisture  favors  the  multiplica- 
tion of  micro-organisms,  resulting  in  putrefactive  changes,  the 
tissue  becoming  dark  brown  or  a  mottled  greenish-black  in 
color  (due  to  disorganized  blood-pigment),  and  distended  with 
gases  produced  by  the  organisms. 

The  Infiltrations  and  Degenerations. 

Though  theoretically  there  is  a  difference  between  a  degene- 
ration and  an  infiltration — the  former  indicating  a  conversion 
of  the  cell-protoplasm  into  a  less  highly  organized  substance, 
rendering  it  less  suited  for  the  performance  of  its  functions, 
while  in  the  latter  there  is  a  substitution  or  deposit  of  some 
new  substance  in  the  cell — practically  it  is  often  difficult  to 
distinguish  between  the  two. 


FATTY  INFILTRATION. 


277 


Fatty  infiltration  may  be  a  physiological  or  a  pathological 
process.  It  occurs  physiologically  under  the  skin,  between 
muscles  and  surrounding  organs ;  pathologically  in  abnormal 
places,  as  between  individual  muscle- fib  res,  and  in  normal 
situations  in  great  excess,  as  in  general  obesity.  It  is  due 
to  either  the  over-production  of  fat  or  its  deficient  consump- 
tion. Fatty  infiltration  of  the  liver  may  be  produced  experi- 
mentally in  the  lower  animals  by  an  excess  of  fatty  food  and 
restriction  of  oxidation  by  preventing  muscular  movement. 
In  phthisis,  cancer,  and  severe  anaemias  the  explanation  seems 
to  be  found  in  lessened  oxidation.  In  chronic  alcoholism  the 
change  often  occurs,  the  alcohol  being  oxidized  in  place  of  the 
fat. 

The  fat-drops  are  larger  than  in  fatty  degeneration,  and  are 
found  either  between  the  tissue-elements  or  within  the  cells, 


FIG.  112. 


Fatty  infiltration  of  muscle  from  a  case  of  stiffening  of  the  ankle  by  an  epithelioma 
of  the  skin  over  it.  The  muscular  fibres  are  narrowed,  and  adipose  tissue  ap- 
pears between  them.  X  80  (Coats). 

the  nucleus  and  protoplasm  being  pushed  one  side  until  the 
cell  is  like  a  vesicle  filled  with  fat  (Fig.  112).  The  liver 
is  frequently  affected  in  advanced  phthisis.  On  section  oil 
accumulates  on  the  knife  or  may  be  scraped  from  the  cut 
surface.  The  affected  organ  is  enlarged,  heavy  but  of  less 
specific  gravity,  soft,  less  elastic  and  doughy,  and  of  a  light 
yellow  color,  or  mottled,  if  the  change  is  not  uniform  through- 
out. In  the  liver  the  change  is  particularly  noted  in  the 
periphery  of  the  acini,  giving  them  a  pale  yellow  margin. 


278  PATHOLOGY  OF  NUTRITION. 

In  fatty  infiltration  of  the  heart  the  muscle-fibres  are  not 
necessarily  affected,  and  consequently  there  is  little  or  no  func- 
tional impairment,  though  by  interfering  with  the  local  blood- 
supply  the  condition  may  become  one  of  fatty  degeneration. 

Fatty  degeneration  is  caused  by  local  interference  with  the 
blood-supply,  anaemias,  and  high  temperature.  Poisons  such 
as  mercury,  arsenic,  lead,  phosphorus,  ether,  chloroform,  and, 
of  still  greater  interest  clinically,  the  toxins  of  micro-organ- 
isms are  frequent  causes.  The  cell  is  shrunken,  not  swollen, 
its  outline  irregular,  and  the  nucleus  destroyed.  The  oil-drops 
are  smaller  and  do  not  tend  to  run  together  as  in  fatty  infiltra- 
tion, appearing  in  the  cell  first  as  small  shining  granules  near 
the  nucleus.  There  is  a  gradual  liquefaction  of  the  cells,  end- 
ing in  their  death. 

Any  tissue  in  the  body,  with  the  exception,  in  the  blood, 
of  the  red  globules,  may  be  affected ;  but  the  parenchyma- 
cells  of  the  liver,  kidney,  heart,  and  central  nervous  system 
most  often — the  interstitial  tissue  being  possibly  later  affected. 

The  fat-drops  are  distinguished  chemically  by  their  insolu- 
bility in  acetic  acid  and  weak  solutions  of  sodium  and  potas- 
sium hydroxide ;  and  by  their  solubility  in  alcohol,  ether,  and 
chloroform,  and  by  staining  black  with  osmic  acid.  Fine  needles 
in  rosettes,  sheaves  of  margaric  acid,  and  rhombic  plates  of 
cholesterin  are  often  found. 

The  organ  affected  is  pale  yellow  or  mottled,  very  anaemic, 
and  feels  greasy  and  soft. 

Amyloid,  lardaceous,  or  waxy  degeneration  is  a  very  fre- 
quent retrograde  change  and  next  to  fatty  degeneration  is  the 
most  common.  It  signifies  the  presence  in  the  tissue  of  a 
colorless,  firm,  translucent,  homogeneous,  inelastic  material  of 
about  the  consistency  of  wax  or  solidified  lard,  to  which,  on 
account  of  its  behavior  toward  iodine,  the  term  " starch-like" 
has  been  given  ;  though  we  now  know  that  it  is  not  a  carbo- 
hydrate, but  a  nitrogenous  compound  (Fig.  113).  If  a  solu- 
tion of  iodine  and  iodide  of  potassum  (LugoPs)  be  applied  to  the 
freshly  cut  surface  of  an  affected  area,  there  results  a  mahogany- 
brown  coloring,  the  surrounding  normal  tissue  being  stained  a 
canary-yellow.  The  addition  of  a  1  per  cent,  solution  of  sulphu- 
ric acid  gives  the  amyloid  material  a  bluish  color.  For  micro- 
scopical sections  a  much  more  satisfactory  staining  reaction  is 


AMYLOID,  LARDACEOUS,  OR    WAXY  DEGENERATION.  279 

found  on  the  addition  of  methyl-  or  gentian-violet,  producing 
a  beautiful  rose-pink,  while  the  normal  tissue  stains  blue. 

The  changes  are  frequently  so  extensive  in  all  the  organs 
in  the  body  and  the  resulting  symptoms  so  numerous  that  it 
is  often  referred  to  as  lardaceous  disease.  The  organs  most 

FIG.  113. 


Amyloid  infiltration  in  the  liver  (Thorna).  a,  lumen  of  an  intralobular  capillary, 
surrounded  by  the  endothelial  wall  of  the  vessel ;  b,  amyloid  substance  imme- 
diately beneath  the  endothelium ;  c.  epithelial  cells  of  the  hepatic  parenchyma, 
some  of  which  show  a  fatty  infiltration. 

frequently  affected  however  are  the  liver,  kidney,  spleen, 
lymphatic  glands,  intestinal  tract  and  suprarenal  capsules. 
The  changes  begin  in  the  inner  coat  of  the  smaller  capillaries, 
and  later  affect  the  cells  and  interstitial  substance  of  the  sur- 
rounding tissue,  extending  along  the  course  of  the  blood- 
vessels. If  extensively  infiltrated,  the  organ  is  increased  in 
size  ;  is  pale,  firm,  and  glistening  in  appearance.  The  change 
may  be  quite  extensive  and  yet  only  noted  on  microscopical 
examination.  The  parenchyma-cells  of  the  organ  swell  and 
become  less  angular. 


280 


PATHOLOGY  OF  NUTRITION. 


The  function  of  the  part  is  impaired  by  reason  of  the  inter- 
ference with  the  blood-supply  and  displacement  of  the  proper 
tissue-elements.  The  spleen  is  usually  the  earliest  organ 
involved,  beginning  in  the  Malpighian  follicles,  which  become 
large,  pale  and  translucent;  and  resemble  grains  of  sago — hence 
the  term  sago-spleen. 

The  condition  occurs  most  frequently  in  connection  with 
long-continued  suppurative  processes ;  with  syphilis  and  tuber- 
culosis ;  and  not  so  frequently  with  other  cachexias — cancer, 
leukaemia,  dysentery,  and  malaria,  and  in  a  few  instances  with- 
out any  apparent  cause. 

Colloid,  mucoid,  and  hyaline  degenerations  are  all  closely 
allied  and  but  little  understood. 

a.  Colloid:  The  prototype  of  this  variety  is  the  colloid 
material  of  the  thyroid  gland  (Fig.  114),  somewhat  similar 

FIG.  114. 


Section  of  thyroid  gland,  showing  colloid  degeneration,  a,  colloid  ;  b,  secreting 
cells  with  granules  (  after  Pozzi). 

in  appearance  to  mucus,  but  firmer.  The  change  affects  mainly 
epithelial  cells  and  is  most  often  seen  in  cystic  goitre  and  in 
new  growths — e.  g.,  colloid  cancer — giving  rise  to  a  gelatinous 
appearance.  In  ovarian  cysts  the  loculi  are  sometimes  filled 
with  colloid  masses. 

b.  Mucoid :  The  physiological  type  of  this  change  is  found 


CLOUDY  SWELLING. 


281 


in  the  mucous  secretions  of  many  glands.  The  change  affects 
both  epithelial  and  connective-tissue  structures,  but  the  latter 
is  of  the  greater  importance 
pathologically.  The  affected 
area  has  a  translucent,  gelati- 
nous, and  swollen  appearance. 

The  most  remarkable  condi- 
tion in  which  it  is  found  is  in 
what  is  known  as  myxcedema, 
the  chief  clinical  characteristic 
of  which  is  a  peculiar  swelling 
of  the  skin  and  subcutaneous 
connective  tissue,  which  differs 
from  ordinary  anasarca  in  not 
pitting  on  pressure. 

c.  Hyaline  degeneration  is 
very  closely  allied  to  amyloid. 
It  occurs  in  connective  tissue 
and  the  walls  of  bloodvessels. 
The  material  has  a  glistening 
waxy  appearance  but  is  less 
translucent  than  amyloid,  the 
staining  reactions  of  which  are 
also  absent. 

Cloudy  swelling,  parenchyma- 
tous  or  granular  degeneration, 
are  terms  used  to  describe  a  re- 
trograde change  in  which  the 
elements  affected,  especially  epi- 
thelial and  muscle  cells,  are 
swollen  and  cloudy  and  filled 
with  minute  albuminous  gran- 
ules. The  outline  of  the  cell 
becomes  indistinct  and  distorted, 
the  nucleus  however  remaining 
often  but  little  altered.  These 
granules  are  insoluble  in  ether, 
but  soluble  in  dilute  acids  and 
caustic  potash.  The  whole  organ  is  swollen,  less  translucent, 
dull  grayish,  cloudy,  and  anaemic — looking  as  if  it  had  been 


Calcareous  infiltration  of  cardiac  mus- 
cle (Langerhans).  a,  degenerated 
cardiac  muscle;  6,  muscular  fibres 
impregnated  with  lime-salts.  The 
specimen  was  taken  from  a  case  of 
chronic  lead-poisoning.  The  cells 
which  are  the  seat  of  the  calcareous 
infiltration  must  have  been  dead  for 
a  considerable  time  before  the  death 
of  the  individual. 


282  PATHOLOGY  OF  NUTRITION. 

boiled.  The  change  may  occur  in  any  organ  in  the  body,  but 
is  most  frequent  in  the  liver,  kidney,  heart-muscle,  and  mucous 
membrane  of  the  gastro-intestinal  tract.  It  occurs  in  all 
inflammations,  in  acute  infectious  diseases,  fever,  after  burns; 
and  in  poisoning  from  phosphorus,  arsenic,  and  mineral  acids. 
The  cells  either  soon  recover  or  the  process  quickly  passes  on 
to  fatty  degeneration. 

Calcareous  infiltration,  or  calcification,  is  the  impregnation  of 
tissues  with  the  salts  of  lime  in  the  form  of  the  insoluble 
carbonate  and  phosphate.  All  parts  are  alike  susceptible, 
both  the  cells  and  intercellular  substance,  though  the  latter  to 

FIG.  116. 


Melanotic  alveolar  sarcoma  of  the  skin,  a,  mononuclear ;  a',  polynuclear  sarcoma- 
cells  with  epithelial  character ;  b,  pigment-cells ;  c,  stroma  with  bloodvessels 
and  pigment.  X  300  (Ziegler). 

the  greater  degree.  The  reason  of  this  deposit  is  not  clear, 
but  it  is  always  connected  with  a  lowered  state  of  nutrition. 
The  tissue  appears  dusted  with  little  fine  granules,  which  in 
the  earliest  stage  might  be  mistaken  for  fat ;  but  they  dissolve 
on  the  addition  of  hydrochloric  acid — and  with  effervescence 
if  the  carbonate  is  present  (Fig.  115). 


PIGMENTARY  INFILTRATION.  283 

These  minute  refractive  granules  enlarge  and  extend,  and  so 
form  dark,  opaque,  granular  patches — white,  grayish,  or  yel- 
low in  color  rnacroscopically.  Physiologically  the  condition 
occurs  in  the  pineal  gland,  choroid  plexus,  in  cartilage  in  old 
age,  and  notably  in  the  development  of  bone.  The  most 
frequent  pathological  sites  are  the  valves  of  the  heart,  arterial 
walls,  caseous  lymph-glands,  and  in  myoma  uteri  when  the 
blood-supply  is  poor.  It  may  be  noted  in  necrotic  tubercular 
foci  and  infarcts. 

Pigmentary  infiltration,  or  abnormal  pigmentations,  depend 
on  both  intrinsic  and  extrinsic  sources  of  supply,  the  former 
being  either  hsematogenous  or  non-hsematogenous. 

1.  Intrinsic:  a.  Hsematogenous.  There  are  twro  varieties 
of  pigment  derived  from  haemoglobin  when  red  blood-cells  are 
destroyed  :  hsemosiderin,  which  contains  iron,  and  hsematoidin, 
which  does  not. 

Hsemosiderin  gives  the  characteristic  chemical  reactions 
of  iron,  and  occurs  in  minute  granules  in  the  liver-cells  in 

FIG.  117. 


Pigmentation  of  the  lung  (from  a  woman,  set.  sixty-five,  with  slight  emphysema), 
showing  the  situation  of  the  pigment  in  the  thickened  alveolar  walls  and  around 
the  bloodvessel,  v.  The  walls  of  the  latter  are  also  thickened  and  its  lumen 
diminished.  X  75  (Green). 

pernicious  ana?mia;  and  is  found  also  in  the  spleen,  renal 
epithelium,  and  medulla  of  bone  in  this  disease,  in  leuka?mia, 
malaria,  severe  cachexias,  in  poisons,  and  septic  processes. 


284  PATHOLOGY  OF  NUTRITION. 

Ha3matoidin  is  found  in  rhombic  crystals  or  granular  in  old 
blood-clots,  free  or  within  leukocytes  and  other  cells. 

b.  Of  non-hsematogenous  pigments,  melanin  is  the  most 
important.  It  is  elaborated  by  living  cells,  and  contains  no 
iron.  Granules  of  melanin  vary  in  color  from  yellow  to  black. 
It  is  noted,  among  other  instances,  in  melanotic  sarcoma  (Fig. 
116). 

2.  Extrinsic :  Extrinsic  sources  of  pigment  are  very  numer- 
ous, the  material  being  absorbed  either  through  the  lungs  or 
gastro-intestinal  tract.  Carbon  is  one  of  the  most  common 
varieties  of  extrinsic  pigment.  When  coal-dust  is  inhaled  it 
gives  rise  to  deposits  of  pigment  in  the  lungs,  the  condition 
being  known  as  coal-miners'  lung,  or  anthracosis  (Fig.  117). 
Siderosis  is  similarly  produced  by  the  inhalation  of  fine  parti- 
cles of  iron,  the  lungs  becoming  rusty  in  color.  In  chalicosis, 
stonemasons7  lung,  the  particles  are  white  and  the  lung  con- 
sequently abnormally  pale. 

In  argyria  silver  is  absorbed  from  the  gastro-intestinal 
tract  and  afterward  deposited  in  the  tissues  as  an  albuminate. 
The  condition  was  more  often  seen  when  silver  was  popular 
in  the  treatment  of  epilepsy  and  other  diseases  of  the  nervous 
system. 

Atrophy. 

The  term  atrophy  means  literally  want  of  food.  The  af- 
fected organ  undergoes  a  more  or  less  uniform  reduction  in  size 
and  weight.  It  may  be  congenital — agenesia — or  acquired. 
In  true  atrophy  there  is  a  decrease  only  in  the  size  of  the  cells 
of  the  tissue,  their  number  remaining  normal.  A  decrease  in 
the  number  of  cells  is  sometimes  spoken  of  as  aplasia,  or 
more  generally  as  numerical  atrophy.  Hypoplasia  is  a  failure 
of  the  cells  to  reach  their  natural  size. 

The  condition  is  seen  physiologically  in  the  thy m us  gland 
in  the  second  year  of  life,  in  the  generative  organs  at  the 
climacteric,  and  in  the  general  atrophy  of  old  age. 

Pathologically  deficient  blood-supply,  if  long  enough  con- 
tinned  but  not  too  severe,  is  an  important  cause.  Under  this 
head  would  come  pressure-atrophy, — e.  g.,  the  absorption  of 
the  bodies  of  dorsal  vertebrae  by  an  aortic  aneurism — and 


HYPERTROPHY.  285 

also  atrophies  from  disease,  as,  for  example,  the  gut  below  a 
lumbar  colotomy,  which  becomes  the  size  of  one's  little  finger. 
There  are  many  instances  of  atrophy  due  to  disturbances  of 
normal  nerve-influences,  as  that  resulting  in  the  salivary  gland 
after  cutting  off  its  nerve-supply. 

Atrophy  is  usually  associated  with  other  degenerative 
changes,  especially  fatty  degeneration  and  calcification.  Ac- 
companying the  atrophy  of  the  cells  proper  of  a  tissue  there 
is  often  an  increase  in  its  connective  tissue,  as,  for  instance,  in 
pseudohypertrophic  paralysis.  In  the  liver  and  kidney  this 
increase  in  connective  tissue — cirrhosis— is  often  looked  upon 
as  an  evidence  of  chronic  interstitial  inflammation  in  contra- 
distinction to  parenchymatous  inflammation. 


Hypertrophy. 

The  term  hypertrophy,  which  properly  means  over-feeding 
or  over-nourishment,  is  applied  to  an  overgrowth  of  an  organ, 
without  marked  alteration  from  the  normal  structure.  It 
implies  more  than  mere  enlargement.  A  carcinomatous  liver 
is  enlarged,  but  not  hypertrophied. 

In  true  hypertrophy  there  is  an  increase  only  in  the  size  of 
the  cells.  Hyper 'plasia,  or  numerical  hypertrophy,  is  an  in- 
crease in  their  number,  their  size  not  being  increased  but 
even  diminished.  Physiologically  this  condition  is  seen  in  the 
enlargement  of  the  uterus  following  impregnation,  and  gigan- 
tism  is  a  remarkable  example  of  general  hypertrophy.  Patho- 
logically, in  leukaemia,  the  spleen  is  found  hypertrophied  to 
several  times  its  normal  size  and  weight. 

Causes  :  Increased  functional  activity,  which  means  also  in- 
creased nourishment,  is  a  most  important  factor  in  the  pro- 
duction of  many  hypertrophies.  When  increased  work  is 
thrown  upon  the  heart,  for  example  as  the  result  of  valvular 
disease,  it  becomes  hypertrophied.  Stricture  of  the  urethra 
causes  hypertrophy  of  the  walls  of  the  bladder.  When  one 
kidney  is  removed  there  is  a  compensatory  hypertrophy  of  its 
fellow.  So  also  when  part  of  a  secreting  gland,  like  the  liver 
or  pancreas,  is  removed  there  is  often  a  hypertrophy  of  the 
remaining  portion. 


286  PATHOLOGY  OF  NUTRITION. 

Fibrosis. 

In  fibrosis,  or  fibroid  substitution,  there  is  a  wasting  of  the 
true  parenchyma-cells  and  an  increase  in  the  connective  tis- 
sue. It  is  not,  strictly  speaking,  a  degeneration  except  in 
that  the  new  material  is  considered  inferior  to  the  original. 
When  the  change  takes  place  in  the  central  nervous  system 
it  is  spoken  of  as  a  sclerosis  ;  in  the  liver  and  kidney,  as  cirrho- 
sis. It  is  often  regarded  as  an  evidence  of  chronic  inflamma- 
tion, for  we  know  that  there  often  results  a  great  increase 
in  the  amount  of  connective  tissue  in  an  area  so  affected.  But 
the  change  often  occurs  where  there  has  been  no  inflammation. 
In  pseudohypertrophic  paralysis,  which  is  not  usually  re- 
garded as  an  inflammatory  process,  the  true  muscle-cells  are 
almost  entirely  atrophied,  yet  by  reason  of  the  increase  in  the 
connective  tissue  the  calves  of  the  legs  are  greatly  enlarged. 
In  fibroid  heart  and  the  various  scleroses  of  the  central 
nervous  system  there  is  considerable  doubt  about  the  inflam- 
matory nature  of  the  change.  In  the  liver  and  kidneys,  how- 
ever, it  is  undoubtedly  a  frequent  sequel  of  long-continued 
inflammations. 

TUMOES. 

Definition :  A  tumor  is  a  non-inflammatory,  circumscribed 
swelling  which  has  no  function. 

Etiology :  Though  a  great  many  theories  have  been  ad- 
vanced, we  actually  know  but  little  as  to  the  causation  of 
tumors.  The  older  authors  referred  to  a  peculiar  constitu- 
tional dyscrasia  in  this  connection.  Yirchow  laid  great  stress 
upon  some  unusual  irritant  as  the  exciting  cause,  as,  for  in- 
stance, cancer  of  the  breast  following  a  blow  or  other  injury 
to  the  part;  or  the  development  of  an  epithelioma  of  the 
tongue  at  the  site  of  chronic  irritation  produced,  for  instance, 
by  a  jagged  tooth.  Cohnheim  advanced  the  theory  that  "  in 
an  early  stage  of  embryonic  development  more  cells  are  pro- 
duced than  are  required  for  building  up  the  part  concerned, 
so  that  there  remains  a  certain  number  unappropriated,  which, 
owing  to  their  embryonic  character,  are  endowed  with  a 
marked  capacity  for  proliferation."  Some  irritant  or  injury 
causes  a  flux  of  blood  to  the  part  and  determines  the  multk 


TUMORS.  287 

plication  of  the  cells,  which  until  that  time  have  remained 
dormant. 

With  regard  to  the  parasitic  origin  of  malignant  tumors, 
the  many  points  of  similarity  in  their  clinical  history  and 
that  of  certain  infectious  diseases,  such  as  tuberculosis,  are  at 
least  very  suggestive.  Should  their  parasitic  origin  be  demon- 
strated they  would  no  longer  be  classed  with  tumors,  but  with 
the  infective  granulomata,  which  they  closely  resemble  in  many 
respects.  The  parasite  of  cancer  is  described  as  a  protozoon. 
The  true  significance  of  the  bodies  so  described  is  as  yet  sub 
judice.  An  epithelioma  has  been  successfully  transmitted 
from  one  animal  to  another  by  artificial  inoculation. 

The  predisposing  influence  of  age  is  an  undoubted  factor, 
some  tumors  only  occurring  at  an  advanced  age,  while  others 
occur  preferably  in  the  young. 

Heredity  plays  a  doubtful  role,  the  importance  of  which  has 
been  greatly  overestimated. 

Classification :  Tumors  have  been  variously  classified. 

Clinically  they  are  divided  into  benign  find  malignant.  The 
former  are  not  dangerous  except  by  reason  of  pressure  they 
may  exert  on  vital  structures,  or  by  mechanically  interfering 
with  the  function  of  a  part,  as,  for  instance,  by  a  tumor  of  the 
brain  or  larynx. 

The  latter  threaten  life  and  are  characterized  by  certain 
well-recognized  criteria  of  malignancy : 

First,  a  tendency  of  the  rapidly  multiplying  cells  of  the 
tumor  to  break  through  normal  barriers  and  spread  locally, 
infiltrating  surrounding  tissues.  This  is  especially  true  of  the 
malignant  variety  of  epithelial  tumors — carcinoma — and  to  a 
less  extent  of  sarcoma,  the  malignant  variety  of  the  con- 
nective-tissue group.  An  adequate  explanation  of  this  charac- 
teristic is  entirely  lacking.  The  imagination  of  one  author 
goes  so  far  as  to  enable  him  to  see  in  the  infiltrating  cells  of  a 
carcinoma  only  a  host  of  invading  parasites.  In  a  child 
some  irritant,  as  dirty  hands,  may  excite  the  multiplication 
of  epithelial  cells,  which,  piling  up  and  cornifying,  constitute 
a  benign  wart ;  while  in  one  advanced  in  years  a  similar  irri- 
tant induces  a  rapid  multiplication  of  epithelial  cells,  which, 
instead  of  piling  up  on  the  surface,  invade  the  underlying 
tissues,  thus  constituting  a  most  malignant  tumor,  a  carci- 


288  PATHOLOGY  OF  NUTRITION. 

noma — e.  g.,  chimney  sweeps'  cancer,  which  seems  to  result 
from  the  accumulation  of  soot  upon  the  scrotum. 

Non-malignant  tumors  are  circumscribed,  often  encapsu- 
lated— facilitating  their  complete  removal.  The  absence  of 
capsule  in  malignant  tumors  and  their  extensive  infiltration 
of  surrounding  tissues  make  their  complete  removal  impossi- 
ble, which  explains  an  important  clinical  characteristic — their 
tendency  to  recur  locally. 

Second,  metastasis,  or  the  occurrence  of  secondary  growths 
in  various  parts  of  the  body,  is  but  an  extension  of  the  ten- 
dency of  malignant  tumors  to  spread  locally.  Tumor-cells 
are  carried  by  way  of  the  lymphatics  or  bloodvessels  to 
distant  parts,  where  they  multiply,  yet  retaining  all  their 
original  characteristics,  such  as  the  tendency  to  horny  degene- 
ration of  the  epidermic  cells  in  some  varieties  of  carcinoma. 
The  number  of  these  secondary  nodules  is  often  so  great  as  to 
remind  one  of  the  lesions  of  general  miliary  tuberculosis. 
Benign  tumors  are  usually  single. 

Third,  cachexia:  A  condition  of  anaemia,  feebleness,  and 
general  impairment  of  nutrition,  which  is  quite  comparable  to 
that  noted  in  tuberculosis  and  other  chronic  infectious  dis- 
eases, is  an  evidence  of  malignancy. 

Fourth,  rapid  growth. 

Fifth :  It  may  be  said  that  the  more  cellular  a  tumor  and 
the  less  its  histological  structure  follows  any  given  type  of 
tissue — i.  e.  the  more  atypical — the  greater  the  probability  of 
its  being  malignant. 

Histological  classification :  Inasmuch  as  the  microscopical 
study  of  tumors  shows  them  to  be  composed  of  no  new  tissue- 
elements,  and  to  conform  more  or  less  closely  to  types  of  tissue 
normally  present  in  the  body,  it  is  quite  natural  to  classify 
them  according  to  their  microscopic  structure.  In  the  study 
of  normal  histology  we  become  acquainted  with  four  types  of 
tissue — connective,  epithelial,  muscle,  and  nervous — and  with 
these  four  varieties  correspond  four  types  of  tumors.  , 

In  the  connective-tissue  group  there  are  the  fibroma,  composed 
of  fibrous  tissue  ;  the  chondroma,  of  cartilage  ;  theosteoma,  of 
bone ;  the  lipoma,  of  fatty  tissue ;  the  myxoma,  of  mucoid  tissue 
similar  to  that  of  Wharton's  jelly  of  the  umbilical  cord  ;  the 
glioma  of  neuroglia ;  the  angeioma  of  bloodvessels ;  and  the 


TUMORS.  289 

lymphangeioma  of  lymphatics.  Corresponding  to  the  two 
types  of  muscle-tissue — the  tinstriped  and  the  striped — we  have 
the  leiorayoma  and  the  rhabdomyoma. 

The  neuromata  find  their  physiological  prototype  in  the 
nerve-fibres  and  ganglion-cells  of  the  central  nervous  system. 

Whereas   connective-tissue   tumors   contain   DO   epithelial 

tissue,    in    another — the    epithelial — group,  the   neoplasm   is 

formed  almost  entirely  of  epithelial  elements,  only  supported 

by  &  framework  of  connective  tissue.     This  group  includes  the 

apilloma,  the  microscopical  structure  of  which  closely  resem- 

es  the  papillae  of  the  skin  or  the  villi  of  the  intestines ;  and 
the  adenoma,  in  which  the  epithelial  cells  are  arranged  in  such 
a  manner  as  to  imitate  normal  glandular  structures  with  a 
certain  degree  of  exactitude. 

On  the  other  hand  the  microscopical  structure  of  the  malig- 
nant tumors—  the  sarcomata  and  carcinomata — does  not 
correspond  with  any  normal  type  of  tissue,  but  is  entirely 
atypical. 

The  sarcoma  is  a  very  cellular  and  highly  vascular  connec- 
tive-tissue tumor  which  histologically  resembles  one  or  another 
stage  of  granulation-tissue,  several  varieties  being  described 
according  to  the  character  of  the  cells  of  which  it  is  formed ; 
the  small  round-celled  sarcoma  having  the  microscopical  ap- 
pearances of  the  earliest  stage  of  granulation-tissue  ;  and  the 
spindle-celled  sarcoma,  that  of  a  later  stage  of  granulation- 
tissue  as  its  development  approaches  fully  formed  fibrous- 
tissue. 

The  carcinoma,  which  is  composed  of  epithelial  cells  atypi- 
cal ly  arranged  in  a  more  or  less  dense  connective-tissue 
stroma,  is  likewise  described  according  to  the  character  of  the 
epithelial  cells  of  which  it  is  composed,  viz.,  the  squamous- 
celled  carcinoma,  or  epithelioma  ;  the  columnar-celled,  or 
adeno-carcinoma,  and  the  sphei^oidal-celled,  or  carcinoma 
simplex. 

AVhen  a  benign  tumor  becomes  malignant  it  still  conforms 
to  its  own  type  of  tissue  ;  that  is  to  say,  one  of  the  connective- 
tissue  group  becomes  sarcomatous  and  not  carcinomatous,  and 
one  of  the  epithelial  group  becomes  carcinomatous  and  not 
sarcomatous. 


19— Hist. 


290  PATHOLOGY  OF  NUTRITION. 


Table : 

1.  Of  Connective  Tissue: 

Fibroma, 

Lipoma, 

Chondroina, 

Myxoma, 

Osteoma, 

Angeioma. 

Malignant — Sarcoma : 

Small  and  large  round  cell, 

Spindle-cell, 

Myeloid, 

Melanotic, 

Alveolar, 

Angeiosarcoma. 

2.  Of  Muscle-tissue : 

Leiomyoma, 
Ehabdomyoma. 

3.  Of  Nervous  Tissue: 

Neuroma. 

4.  Of  Epithelial  Tissue  : 

Papilloma, 

Adenoma. 

Malignant — Carcinoma : 

Squamous-celled — Epithelioma, 
Cylindrical-celled — Adenocarcinoma, 


Spheroidal-celled — Carcinoma  Simplex  j  J2ncephal 


A  fibroma  is  a  tumor  of  fibrous  connective  tissue,  according 
to  the  density  of  which  hard  and  soft  varieties  are  distin- 
guished. The  former  is  composed  almost  entirely  of  dense 
interlacing  bundles  of  fibres  and  may  be  as  hard  as  cartilage 
(Fig.  118).  Between  the  fibres  are  a  few  compressed  or 
spindle-shaped  cells.  In  the  soft  variety  round,  spindle,  and 
branching  cells  are  numerous,  and  the  fibres  few  in  number 
with  wider  meshes.  All  gradations,  however,  are  met  with 
between  the  two,  and  in  its  cellular  richness  it  may  approach  a 
fibrosarcoma. 

These  tumors  always  grow  from  preexisting  connective 
tissue.  Their  most  frequent  seats  are  the  skin  and  subcutane- 
ous connective  tissue,  the  sheaths  of  nerves  and  tendons,  and 
the  periosteum  of  bones.  They  are  also  found  growing  from 
the  connective-tissue  framework  of  the  mammae,  ovaries, 


MYXOMA. 


291 


uterus,  and  kidneys.     They  are  liable  to  undergo  mucoid  and 
fatty  degeneration. 


FIG.  118. 


Section  of  a  nodular  fibroma  (Birch-Hirschfeld).  The  dense  fibrous  tissue  is  in 
irregular  nodules,  between  which  are  bands  of  less  dense  fibrous  tissue  con- 
taining bloodvessels. 

'-   ? 

A  lipoma  is  a  tumor  composed  of  fatty  tissue,  similar  to 
normal  adipose  tissue,  except  that  the  fat-cells  are  larger, 
contain  more  oil,  and  are  not  so  regularly  arranged.  They 
are  tabulated,  often  grow  to  enormous  size,  and  sometimes  are 
multiple  (Fig.  119).  They  are  most  common  in  the  sub- 
cutaneous fatty  tissue  of  the  back,  shoulders,  and  buttocks. 
They  are  liable  to  myxomatotis  and  cystic  degeneration  and 
calcification. 

A  myxoma  is  a  tumor  composed  of  mucous  tissue — similar 
to  that  of  AVharton's  substance  of  the  umbilical  cord  and  the 
vitreous  humor  of  the  eye,  which  consists  of  a  gelatinous, 
homogeneous,  or  slightly  granular  matrix  crossed  by  fine 
fibrilla?,  in  which  are  imbedded  irregular  branching  and 


292 


PATHOLOGY  OF  NUTRITION. 


anastomosing  stellate  or  spindle-shaped  connective-tissue  cells 
(Fig.  120). 

But  few  tumors  are  entirely  myxomatous,  being  combined 
with  other  forms  of  connective  tissue,  constituting  fibromyxoma, 
lipomyxoma,  chondromyxoma,  myxosareoma,  etc. 


FIG.  119. 


Lipoma  of  the  kidney  (Birch-Hirschfeld).  The  boundary  between  the  adipose 
tissue  of  the  tumor  and  the  renal  tissue  is  not  sharply  defined.  The  former 
occupies  the  middle  of  the  section  and  extends  to  its  lower  edge. 

They  are  found  in  submucous  and  subcutaneous  tissue,  in 
the  mammary  and  parotid  glands,  and  marrow  of  bone. 

A  chondroma  is  a  tumor  composed  of  hyaline,  elastic,  or 
fibro-cartilage  or  more  frequently  of  a  combination  of  these 
varieties  of  normal  cartilage,  differing  therefrom  in  that  the 
cells  are  much  less  regularly  arranged.  Hyaline  cartilage  is 
the  form  most  frequently  found  (Fig.  121).  If  they  occur 
in  situations  in  which  cartilage  normally  exists,  they  are  called 
ecchondromata,  or  cartilaginous  outgrowths.  When  they  occur 


OSTEOMA. 


293 


in  other  situations,  as  in  the  testicle,  parotid  and  mammary 
glands,  they  are  called  enchondromata.  They  are  liable  to 
calcification  and  retrograde  changes. 


FIG.  120. 


FIG.  121, 


Myxoma  (from  the  arm),  showing  the 
characteristic  branched  anastomos- 
ing cells,  a  few  leukocytes,  and  one 
or  two  spindle-cells.  X  200  (Green). 


Hyaline    chondroma. 
(Green). 


X    200 


FIG.  122. 


Ivory  exostosis 


ne,  natural  size  (Ziegler). 


An  osteoma  is  a  tumor  composed  of  bone,  and  may  be  of 
either  the  dense  or  cancellons  variety.  It  is  said  to  be 
heterologus  when  occurring  in  organs  unconnected  with  bone, 


294  PATHOLOGY   OF  NUTRITION. 

as  in  the  skin,  lungs,  meninges,  testicle,  and  parotid  gland.  If 
occurring  as  an  outgrowth  from  bone,  they  are  known  as  ex- 
ostoses  (Fig.  122). 

Angeioma, 

An  angeioma  is  a  tumor  composed  mainly  of  bloodvessels. 
There  are  two  varieties — simple  and  cavernous.  In  simple 
angeioma,  or  leleangiectasis,  there  is  an  abundant  plexus  of  ar- 
teries, veins,  and  capillaries  as  found  in  the  skin  in  ncevi. 
They  also  occur  on  mucous  surfaces  and  rarely  in  the  internal 
organs. 

Cavernous  angeioma,  which  is  the  more  common  variety,  re- 
sembles microscopically  the  tissue  of  the  corpus  cavernosum 
of  the  penis,  being  made  up  of  large,  irregularly  shaped,  in- 
tercommunicating spaces  filled  with  blood,  lined  by  endothe- 
lium,  and  separated  from  each  other  by  connective-tissue  par- 
titions. They  are  most  common  in  the  liver,  but  are  found 
also  in  the  spleen,  kidney,  and  uterus. 

Lymphangeiomata  are  formed  of  dilated  lymphatic  vessels 
identical  in  structure  with  the  hsemangeiomata.  Cavernous 
lymphangeiomata  have  been  occasionally  found  in  the  kidneys 
and  lymphatic  glands.  In  congenital  enlargement  of  the 
tongue — macroglossia,  and  of  the  lips — macrocheilia,  and  in 
elephantiasis,  there  is  a  diffuse  dilatation  of  lymphatic  struct- 
ures. 

Sarcoma. 

A  sarcoma  is  a  richly  cellular  malignant  tumor  of  the  con- 
nective-tissue group,  which,  histologically,  resembles  granula- 
tion— i.  e.j  embryonic  or  undeveloped  connective  tissue.  The 
cells,  round  and  spindle-shaped,  are  greatly  in  excess  of  the 
intercellular  substance.  The  more  cellular  its  structure  the 
greater  the  malignancy  of  the  growth.  Though  the  amount 
of  the  intercellular  substance  may  be  very  scant,  yet  it  may 
be  of  such  quantity  and  character  as  to  give  rise  to  special 
varieties — fibrosarcoma,  myxosarcoma,  chondrosarcoma,  and 
osteosarcoma.  The  bloodvessels,  which  in  some  instances  are 
extremely  abundant,  are  simple  channels  lined  with  a  single 
layer  of  cells. 


ROUND-CELLED  SARCOMATA. 


295 


Sarcomata  are  liable  to  retrograde  metamorphoses — fatty 
degeneration,  caseation,  liquefaction,  and  liberation.     Accord- 


FIG.  123. 


Small  round-celled  sarcoma  of  the  neck.  Section  only  moderately  magnified,  show- 
ing the  extremely  cellular  character  of  the  growth  ;  the  great  friability  of  the 
tissue  is  owing  to  the  minimal  amount  of  intercellular  substance  it  contains  and 
the  intimate  relations  between  the  tissue  of  the  tumor  and  the  walls  of  rela- 
tively large,  thin-walled  bloodvessels  (Dunham). 

ing  to  the  character  of  the  predominant  cells,  several  varieties 
are  described  : 

Round-celled  sarcomata  have  their  prototype  in  the  early 

FIG.  124. 


«fc*^/«»:A  *A* 


Large  round-celled  sarcoma  of  the  tongue,  a,  large  round  cell  containing  three 
nuclei ;  b,  delicate  fibrous  stroma  supporting  the  cells  of  the  growth.  At  the 
point  b  this  stroma  contains  a  collapsed  capillary  bloodvessel.  The  large  round 
cells  are  probably  of  endothelial  origin.  The  growth  occurred  in  a  man  aged 
sixty -one  years,  and  in  the  course  of  eight  mouths  had  attained  the  size  of  a 
hickory -nut  (Dunham). 


296  PATHOLOGY  OF  NUTRITION. 

stage  of  granulation-tissue.  The  cells  are  about  the  size  of 
leukocytes,  with  large  nuclei  and  but  little  cytoplasm,  though 
sometimes  they  are  formed  of  larger  spherical  cells.  There 
is  scarcely  any  stroma  between  the  cells  (Figs.  123  and  124). 
The  tumor  is  gray  or  pink  in  color,  usually  quite  soft,  and  is 
found  most  commonly  in  the  skin,  testicle,  eye,  ovary,  perios- 
teum, bone,  and  subcutaneous  connective  tissue.  When  they 
occur  in  lymph-glands  and  adenoid  tissue  of  mucous  mem- 
branes they  are  designated  lymphosarcomata,  on  account  of  the 
appearance  of  their  supporting  stroma.  Metastasis  takes 
place  through  the  bloodvessels,  secondary  growths  occurring 
most  frequently  in  the  lungs. 

Spindle-celled  sarcomata  have  their  prototype  in  a  more 
advanced  stage  of  granulation-tissue — the  transitional  stage 
between  granulation-tissue  and  young  cicatricial  tissue;  the 

FIG.  125. 


Large  spindle-celled  sarcoma  (Birch-Hirschfeld). 

cells  are  elongated  or  spindle-shaped  and  often  irregular 
and  provided  with  several  processes  (Fig.  125).  They  grow 
from  dense  connective  tissues,  as  periosteum,  intermuscular 
septa,  fasciae,  and  tendons,  are  firmer  in  consistency,  and  grow 
less  rapidly  than  the  round-celled  variety.  The  amount  and 
character  of  the  intercellular  substance  in  this  and  other  types 


ANGEIOSARCOMATA.  297 

of  sarcoma  vary ;  they  may  be  such  as  to  suggest  the  term 
fibrosarcoma,  myxosarcoma,  chondrosarcoma,  etc. 

Giant-celled  or  myeloid  sarcomata  are  characterized  by  the 
presence  of  large,  flat,  irregularly  shaped,  multinucleated  cells, 

FIG.  126. 


Giant-celled  sarcoma  of  the  superior  maxilla :  epulis.  a,  large  giant-cell,  with  numer- 
ous nuclei ;  b,  tangential  section  of  a  similar  cell.  Aside  from  the  giant-cells, 
the  growth  is  composed  of  spindle-cells  and  a  moderate  amount  of  a  fibrous  in- 
tercellular substance.  The  tumor  was  removed  from  a  man  forty-one  years  of 
age,  and  was  of  slow  growth,  having  attained  the  size  of  a  filbert  in  two  and  a 
half  years  (Dunham). 

and  arise  most  frequently  from  the  marrow  or  periosteum 
of  bone  (Fig.  126).  They  are  of  slow  growth  and  less 
malignant  than  the  other  varieties,  though  metastasis  may 
occur. 

Alveolar  sarcoma  is  a  very  malignant  variety,  which  bears  a 
close  resemblance  to  cancer  in  that  the  cells  are  arranged  in 
an  alveolar  fibrous  stroma.  The  cells,  however,  are  not  of  an 
epithelial  type,  and  are  separated  from  each  other  by  fine  tra- 
becula?  extending  in  from  the  alveolar  walls  (Fig.  127).  They 
are  most  frequent  in  the  skin,  occurring  also  in  lymphatic 
glands  and  serous  membranes. 

Angeiosarcomata  arise  from  the  adventitia  of  bloodvessels, 
which  are  surrounded  by  the  masses  of  proliferating  round 


298 


PATHOLOGY  OF  NUTRITION. 


cells.  They  occur  in  serous  membranes,  skin,  brain,  breast, 
and  salivary  glands.  They  are  relatively  benign,  metastasis 
being  very  rare. 

Endothelial    sarcomata,    or    endotheliomata,    are   composed 
of   concentrically   arranged   cells,    strongly    resembling    the 


FIG.  127. 


Melanotic  alveolar  sarcoma  of  the  skin,  a,  mononuclear ;  a',  polynuclear  sarcoma- 
cells  with  epithelial  character ;  b,  pigment-cells ;  c,  stroma  with  bloodvessels 
and  pigment.  X  300  (Ziegler). 

endothelial  cells  lining  the  lymph-vessels  and  spaces  from 
which  they  have  developed  (Fig.  128).  Degenerative  changes 
and  subsequent  calcareous  infiltration  give  origin  to  the 
so-called  psammomata  or  "sand  tumors"  of  the  brain. 
They  occur  in  the  pleura,  peritoneum,  and  meninges  of  the 
brain. 

Melanotic  sarcoma  is  an  exceedingly  malignant  variety 
arising  from  pigmented  tissues,  such  as  the  skin,  choroid  coat 
of  the  eye,  and  pia  mater.  Its  structure  may  be  that  of  any  of 
the  above  varieties,  though  it  is  usually  spindle-celled.  The 
secondary  metastatic  growths  are  likewise  pigmented  and 
of  similar  structure. 


PAPILLOMA. 


299 


Papilloma  and  Adenoma. 

A  papilloma  is  a  wartlike  excrescence  composed  of  papillae 
resembling  those  of  the  skin  and  mucous  membranes  or  the 

FIG.  128. 


Endothelioma  from  the  floor  of  the  mouth  (Earth).  Older  portion  of  the  growth. 
This  has  a  general  alveolar  structure,  the  alveoli  being  separated  by  a  vascular- 
ized  areolar  tissue,  n,  n,  necrosed  groups  of  endothelial  cells ;  h,  h,  similar  ne- 
crosed masses  that  have  undergone  hyaline  degeneration. 

FIG.  129. 


Section  of  wart  of  skin,   a,  coriuni;  b,  enlarged  papillae;  c,  stratified  horny  layer. 

X  40  (Ziegler). 


300 


PATHOLOGY   OF  NUTRITION. 


villi  of  the  intestines,  and  surmounted  by  epithelium.  It  may 
be  a  simple,  smooth  elevation,  or  have  a  cauliflower  appear- 
ance (Fig.  129).  They  occur  especially  in  the  bladder,  gastro- 
intestinal tract,  larynx,  and  nose. 

An  adenoma,  as  its  name  implies,  is  a  tumor  which,  histo- 
logically,  more  or  less  closely  resembles  normal,  tubular,  or 
acinous  glandular  structures  (Fig.  130).  The  absence  of 

FIG.  130. 


Adenoma  of  mamma,  a,  acini ;  6,  ducts ;  c,  well-marked  connective-tissue  stroma. 

X  30  (Ziegler). 

excretory  ducts  often  leads  to  cystic  dilatation  of  the  tubules 
or  acini,  from  the  accumulation  of  the  secretions  of  the 
glandular  elements,  giving  rise  to  the  term  cysto-adenoma. 
From  the  walls  of  such  cysts  papillary  outgrowths  may 
occur. 

Adenomata  are  benign,  though  in  some  cases  there  may  be 
metastasis.  Their  most  frequent  situations  are  the  skin,  mu- 
cous membranes,  mammae,  kidneys,  ovaries,  liver,  thyroid,  and 
prostate  gland.  In  the  ovaries  they  are  supposed  to  be  the 
origin  of  ovarian  cysts,  which  often  reach  an  enormous  size. 


CARCINOMA.  301 

Adenoma  of  the  liver  probably  arises  from  the  bile-ducts,  as 
its  epithelial  elements  differ  "in  structure  from  the  hepatic 
cells. 

Carcinoma. 

A  carcinoma,  or  cancer,  is  the  malignant  variety  of  the  epi- 
thelial-tissue group  of  tumors.  The  arrangement  of  the  rap- 
idly multiplying  epithelial  cells,  of  which  the  tumor  is  mainly 
composed,  with  reference  to  the  connective-tissue  stroma  is 
atypical,  peculiar  to  carcinoma — not  seen  in  any  other  tissue 
in  the  body,  though  often  suggestive  of  glandular  structures. 
The  cells  originate  from  surface  or  glandular  epithelium ; 
breaking  through  normal  anatomical  boundaries,  they  infiltrate 
the  surrounding  connective  tissue,  which  in  its  turn  thus  pro- 
liferates, and  thus  their  mutual  interpenetration  gives  rise  to 
the  microscopical  structure  which  is  always  diagnostic  of  carci- 
noma—epithelial cells  in  an  alveolar  stroma.  The  cells  are  very 
apt  to  retain  to  a  certain  extent  the  characteristics  of  those 
from  which  they  originated  :  if  from  one  of  the  glands  of  the 
stomach,  the  new-formed  cells  also  are  cylindrical,  and  often 
seem  to  attempt  to  reproduce  glandular  tissue — i.  e.,  there  are 
variously  shaped  spaces  more  or  less  regularly  lined  by  epi- 
thelium. If  from  the  epidermis,  the  newly-formed  squamous 
cells  may  show  the  same  tendency  to  cornification. 

The  amount  of  the  stroma  varies  ;  if  considerable,  the 
growth  is  hard — scirrhous;  if  scanty,  it  is  soft  and  brain-like 
— encephaloid;  further,  it  is  often  quite  cellular  from  the 
presence  of  infiltrating  leukocytes  or  newly-formed  connective- 
tissue  cells.  Metastasis  occurs  through  the  lymphatics,  while 
in  sarcoma  it  occurs  through  the  bloodvessels.  The  secon- 
dary growths  have  the  same  general  structure  as  the  primary. 

Carcinoma  occurs  most  frequently  between  the  ages  of 
forty-five  and  sixty-five,  and  is  found  most  frequently  in  the 
uterus,  gastro-intestinal  tract,  skin,  mammary  gland,  ovary, 
and  occasionally  in  the  liver,  kidney,  thyroid,  and  prostate 
gland.  It  is  quite  liable  to  retrograde  changes — fatty  and 
colloid  degeneration,  necrosis,  and  ulceration. 

Several  varieties  are  described  according  to  the  character 
of  the  epithelial  elements — squamous,  cylindrj^*. 
— which  compose  the  tumor : 


LI  BR  ARY 


302 


PATHOLOGY  OF  NUTRITION. 


Carcinoma  simplex,  or  spheroidal-celled  cancer,  arises  in 
glands  with  spheroidal  epithelium,  as,  for  example,  the  mam- 
msa.  The  acinous  or  glandular  arrangement  of  the  tissue 
from  which  it  grows  is  soon  obscured  and  replaced  by  the 
perfect  alveolar  structure  typical  of  cancer.  In  the  earliest 
stage  of  its  growth  there  would  be  simply  noted  at  a  given 
point  within  an  acinus  a  proliferation  and  piling  up  of  the 
epithelial  cells.  Soon  they  break  through  the  basement-mem- 
brane and  infiltrate  the  surrounding  connective  tissue.  The 
cells  are  generally  spheroidal  unless  altered  by  mutual  press- 
ure. According  to  the  density  of  the  connective-tissue  stroma, 
two  varieties  are  distinguished,  the  scirrhous  and  encephaloid. 

In  the  scirrhous  variety  the  epithelial  element  is  relatively 
small ;  the  tumor  is  hard  and  grows  slowly  (Fig.  131).  In 

FIG.  131. 


Scirrhous  of  mamma.     X  100  (Ziegler). 

encephaloid  the  stroraa  is  scanty,  the  tumor  of  soft  consis- 
tency and  rapid  growth  (Fig.  132). 

Cylindrical-celled  cancer,  or  adenocardnomaf  arises  from 
surfaces  covered  with  cylindrical  epithelium,  as  from  the 
glands  of  the  gastro-intestinal  tract.  Especially  in  the  early 


SQUA MO  US-CELLED  CANCER.  303 

stage  of  development,  its  general  structure  is  distinctly  gland- 
ular, consisting  of  tubular  or  rounded  gland-like  spaces  or 
alveoli  lined  with  cylindrical  epithelium.  It  is  distinguished 
from  simple  adenoma,  however,  which  it  greatly  resembles, 
by  the  irregular  arrangement  of  the  marginal  epithelium,  by 
the  masses  of  epithelial  cells  which  often  completely  fill  the 
lumen  of  the  alveoli,  especially  in  the  older  parts  of  the 

FIG.  132. 


Medullary  carcinoma  of  the  mammary  gland  (Hansemann).  The  stroma  of  the 
tumor  is  here  reduced  to  a  minimal  amount  of  areolar  tissue  containing  the 
vascular  supply  of  the  growth. 

tumor,  and  by  epithelial  cells  which  have  broken  through  the 
basement-membrane  and  infiltrated  the  connective-tissue 
stroma  between  the  alveoli. 

Squamous-celled  cancer,  or  epithelioma,  arises  from  surfaces 
covered  by  stratified  squamous  epithelium,  as  from  the  skin, 
oesophagus,  larynx,  lips,  etc.  The  proliferating  epithelial 
cells  show  the  characteristic  tendency  noted  in  all  cancers  to 
extend  beyond  normal  limits  and  infiltrate  adjacent  tissues. 
The  tumor  is  found  to  be  composed  of  masses  of  flat  epithelial 
cells  grouped  in  conical  or  irregularly  shaped  processes  or 
columns  of  variable  length  and  breadth,  simple  or  branching, 
and  separated  from  one  another  by  a  scanty  connective-tissue 
stroma.  At  many  places  in  the  deeper  parts  of  the  tumor,  as 


304 


PATHOLOGY  OF  NUTRITION. 


the  result  of  the  pressure  exerted  by  the  rapid  cell-prolifera- 
tion and  the  lack  of  space,  the  flat  cells  are  found  on  edge 
and  concentrically  arranged  in  whorls,  which  often  have  a 
glistening  appearance  as  the  result  of  a  horny  transformation 
or  cornification — constituting  the  so-called  "  pearly  bodies" 
(Fig.  133). 

Epitheliomata  appear  as  elevated  nodular  masses  or  diffuse 
infiltrations  of  rather  slow  growth,  very  prone  to  ulceration 

FIG.  133. 


Epithelial  pearl-body  from  an  epithelioma  of  the  lip.  a,  pearl-body ;  b,  surrounding 
epithelium,  forming  one  of  the  epitheliomatous  tongues  or  co'lumns  ;  c,  round- 
celled  infiltration  of  the  contiguous  fibrous  tissue  (Dunham). 

and  great  destruction  of  tissue.  Metastasis  may  occur,  but  is 
not  common.  The  term  colloid  cancer  is  applied  to  any  of 
the  above  forms  which  has  undergone  a  colloid  degeneration. 

Myoma. 

A  myoma  is  a  tumor  composed  of  muscle-tissue.  There  are 
two  varieties,  corresponding  to  the  two  varieties  of  muscle- 
tissue — rhabdomyoma,  formed  of  striped,  and  leiomyoma,  of 
unstriped  muscle-tissue. 

Rhabdomyomata  are  exceedingly  rare.     In  a  few  instances 


LEIOMYOMATA. 


305 


such  tumors  have  occurred  congenitally  in  the  heart  and  caused 
death.  Such  tumors  have  also  been  found  in  the  kidney, 
mixed  with  sarcomatous  tissue  and  malignant  in  proportion  to 
the  amount  of  the  latter  (Fig.  134). 

Leiomyomata  are  of  much  more  common  occurrence — the 
most  frequent  seat  being  the  uterus,  though  they  may  occur 
wherever  unstriped  muscle-tissue  is  normally  found.  They  are 
formed  of  bundles  of  muscle-cells,  closely  packed  and  inter  - 

FIG.  134. 


Rhabdomyosarcoma  of  the  kidney,  a,  a,  a,  imperfectly  developed  striated  muscle- 
fibres  ;  b,  tissue  composed  of  small  round  and  spindle-shaped  cells,  separated  by 
considerable  delicate  fibrous  intercellular  substance.  In  other  parts  of  the  growth, 
which  was  the  size  of  the  fist,  this  tissue  was  more  distinctly  sarcomatous  and 
the  amount  of  muscular  tissue  smaller.  The  child  from  which  this  tumor 
was  removed  was  about  two  years  old. 

lacing  in  every  direction.  When  there  is  a  large  amount  of 
connective  tissue  between  the  bundles  they  are  termed  fibro- 
myomata.  On  account  of  the  wavy  course  of  the  muscle- 
cells,  in  microscopical  section  they  seldom  are  seen  in  their 
entire  length,  though  they  may  be  isolated  by  teasing  out  a 
portion  of  the  tumor.  The  characteristic  feature  is  the 
presence  of  the  long  rod-shaped  nuclei — circular,  however, 
if  cut  transversely  (Fig.  135).  Their  appearance  suggests 
spindle-celled  sarcoma,  but  in  the  latter  the  cells  are  not 

20— Hist. 


306 


PATHOLOGY  OF  NUTRITION. 


arranged  in  regular  bundles  and  their  nuclei  are  not  oblong, 
but  oval ;  sarcomatous  transformation,  however,  may  occur. 
Myxomatous  degeneration  and  calcification  are  the  most  fre- 
quent retrograde  changes  to  which  they  are  liable. 


FIG.  135. 


Leiomyoma  of  the  uterus  (Birch-Hirschfeldj. 


Neuroma  and  Glioma. 

A  true  neuroma  is  a  very  rare  tumor,  composed  of  nerve- 
fibres  and  ganglion-cells.  The  so-called  false  neuromata  are 
usually  fibromata  occurring  in  the  course  of  a  nerve  and 
found  also  as  bulbous  swellings  of  the  cut  ends  of  the  nerves 
in  amputated  limbs. 

A  glioma  is  a  tumor  composed  of  tissue  similar  to  neuroglia, 
occurring  in  the  brain  and  less  frequently  in  the  spinal  cord 
and  the  retina  of  the  eye.  They  are  formed  of  a  very  delicate 
network  of  fibres,  imbedded  in  which  are  numerous  round 
or  oval  cells  with  very  large  nuclei.  They  are  benign,  though 
liable  to  undergo  sarcomatous  transformation. 


CYSTS. 

Teratoma. 


307 


Teratomata  are  tumors  of  complex  structure,  sometimes 
consisting  of  a  mingling  of  several  types  of  tissue  as  gland, 
nervous,  muscle,  and  connective  tissue  ;  sometimes  being  com- 
posed of  more  or  less  complete  organs,  as  breasts,  nerves, 


FIG.  136. 


Dermoid  cyst  of  the  ovary,  showing  all  the  structures  of  true  skin  except  sweat- 
glands— viz.,  epithelium,  rudimentary  papillae,  fibrous  tissue  or  cutis  vera,  hair- 
follicles,  large  sebaceous  glands.  X  18  (Boyd;. 

muscles,  portions  of  intestine — constituting  so-called  dermoid 
tumors,  which,  however,  usually  present  themselves  as  cysts 
filled  with  hair,  teeth,  and  occasionally  bone,  muscle-  and 
nerve-tissue.  Teratomata  also  include  certain  malformations 
and  monstrosities  (Fig.  136). 

CYSTS. 

A  cyst  is  a  cavity,  usually  with  a  distinct  membranous  wall, 
which  contains  a  fluid  or  semifluid  material.  They  are  not 
really  tumors,  though  usually  considered  in  connection  with 
the  latter.  They  are  generally  classified  according  to  the 
method  of  their  formation. 


308  PATHOLOGY  OF  NUTRITION. 

Retention-cysts  result  from  the  accumulation  or  retention  of 
the  natural  secretion  of  a  gland,  due  to  the  obstruction  of  its 
duct.  As  examples  may  be  mentioned  sebaceous  cysts  or 
wens ;  and  ranula,  which  results  from  obstruction  of  the  ducts 
of  the  salivary  gland.  As  the  result  of  obstruction  of  a  ureter 
the  whole  kidney  may  be  converted  into  a  cyst. 

Disintegration-cysts  result  from  degenerative  softening  and 
disintegration  of  normal  or  pathological  tissues.  This  may 
occur  after  hemorrhage  into  the  brain — apoplectic  cyst.  Para- 
sitic cysts  might  be  included  under  this  head — for  example, 
hydatid  cysts.  Tumors,  especially  sarcomata  and  chondro- 
mata,  are  liable  to  cystic  degeneration. 


SPECIAL  PATHOLOGY. 


CHAPTER    III. 
DISEASES  OF  THE  BLOOD. 

PLETHORA. 

THE  condition  of  plethora,  by  which  is  understood  an  excess 
of  blood  in  the  body,  was  regarded  by  the  older  writers  as  of 
great  importance,  and  most  serious  consequences  were  at- 
tributed to  it.  Clinically,  its  presence  was  supposed  to  be 
indicated  by  redness  of  the  face  and  a  vigorous  circulation 
occurring  in  high  livers. 

Experimental  evidence  goes  to  show  that  if  the  amount  of 
blood  in  the  vessels  is  artificially  increased  the  result  is  but 
temporary,  as  the  excess  is  carried  off  by  the  kidneys  in  a  few 
hours. 

OLIGEMIA. 

The  term  oligemia  indicates  a  diminution  in  the  total  quan- 
tity of  blood.  This  undoubtedly  does  occur  after  profuse 
hemorrhages,  severe  vomiting,  and  diarrhoea.  There  is  rea- 
son to  believe  it  exists  in  starvation  and  certain  cachectic 
conditions. 

QUALITATIVE  CHANGES  IN  THE  BLOOD. 

Alterations  in  the  plasma:  The  amount  of  fibrin  formed 
from  the  blood  was  carefully  investigated  in  the  days  of 
frequent  venesection.  It  is  greatly  increased  in  certain  acute 
inflammations,  as  pneumonia,  pleurisy,  and  peritonitis.  In 
some  infectious  diseases,  as  typhoid  and  smallpox,  the  amount 
of  fibrin  is  not  increased ;  though  if  a  pneumonia  or  pleurisy 
occurs  as  a  complication  such  an  increase  is  immediately 
noted.  A  reduction  of  the  fibrin-forming  property  of  the 
blood  has  been  occasionally  observed,  as  in  purpura  and 

309 


310  DISEASES  OF  THE  BLOOD. 

scurvy.  Our  knowledge  regarding  chemical  changes  in  the 
plasma  is  exceedingly  meagre. 

Alterations  in  the  red  corpuscles  :  Polycythcemia  or  erythro- 
cytosix,  in  which  there  is  an  actual  increase  in  the  number  of 
red-cells  in  a  given  bulk  of  blood,  is  of  relatively  rare  occur- 
rence. Hay  era  states  that  they  may  be  increased  from  the 
normal  five  million  to  six  and  a  half  million  per  cubic  milli- 
metre in  the  algid  stage  of  cholera. 

Oligocythamta,  in  which  there  is  a  reduction  in  the  number 
of  red  cells,  is  very  frequently  noted.  It  may  occur  tempo- 
rarily from  a  considerable  loss  of  blood,  or  permanently  as 
the  result  of  interference  with  the  formation  of  the  red 
globules  in  the  body.  According  to  Hay  em,  if  the  condition 
is  brought  about  rapidly,  as  by  hemorrhage,  a  reduction  in 
their  number  beyond  one  million  per  cubic  millimetre  is  almost 
certain  to  prove  fatal.  When  this  reduction  is  progressive  the 
body  seems  to  adapt  itself  to  these  new  conditions,  patients 
being  seen  active  and  earning  their  living  with  less  than  two 
million  red  blood-cells  per  cubic  millimetre.  Extreme  and 
fatal  cases  have  been  recorded  in  which  there  were  less  than 
three  hundred  thousand  per  cubic  millimetre. 

Alterations  in  the  size  and  shape  of  the  red  corpuscles  are 
frequent.  Their  normal  average  diameter  is  seven  and  a  half 
microns — 7.5  p.  (IJL=  ToVfr  millimetre). 

Microcytes  are  dwarf  corpuscles  two  to  five  microns  in 
diameter.  Macrocytes,  or  megalocytes,  are  giant-cells  nine  to 
twenty  microns  in  diameter.  Poikilocytes  are  oval,  pear- 
shaped,  or  variously  distorted  corpuscles.  Erythroblasts  are 
nucleated  red  blood-cells,  which  are  termed,  according  to  their 
size,  normoblastSj  microblasts,  and  megaloblasts. 

While  the  normoblasts  occur  normally  in  bone-marrow,  and 
would  seem  to  be  present  in  the  circulation  in  this  immature 
form  as  the  result  of  an  unusual  effort  on  the  part  of  the 
blood-making  organs  to  improve  the  blood,  the  megaloblasts 
are  never  present  in  healthy  adult  marrow,  and,  as  they  do 
not  develop  into  mature  corpuscles,  they  are  looked  upon  as  a 
degenerative  type. 

The  microblasts  are  not  so  frequently  met  with  as  the  other 
two  varieties.  Karyokinetic  figures  are  sometimes  seen  in 
the  nuclei  of  erythroblasts. 


CHANGES  IN  THE  BLOOD.  311 

Red  blood-corpuscles  have  an  especial  affinity  for  eosin  and 
other  acid  stains,  and  in  a  mixture  of  dyes,  such  as  haema- 
toxylin  and  eosin,  stain  only  with  one  of  them,  the  eosin, 
which  property  is  termed  monochromatophilia.  Pathologi- 
cally, however,  they  may  develop  an  affinity  also  for  basic 
dyes ;  when  stained  with  haematoxylin  and  eosin  mixture  they 
present  a  violet  or  purple  color,  instead  of  the  normal  pink — 
this  is  termed  polychromatophilia. 

Alterations  in  the  leukocytes :  Hypoleukocytosis  or  letiko- 
penia — a  deficiency  in  the  number  of  leukocytes — is  associated 
with  certain  conditions,  as,  long-continued  fevers,  like  typhoid, 
when  uncomplicated  by  inflammatory  processes ;  with  tuber- 
culosis and  inanition. 

Leukocytosis — a  transient  increase  in  the  number  of  leuko- 
cytes above  the  normal  ten  thousand  per  cubic  millimetre — is 
noted  in  connection  especially  with  inflammatory  processes 
and  infectious  diseases.  The  degree  of  the  leukocytosis  in 
pneumonia  and  most  inflammatory  affections  is  regarded  as 
an  index  of  nature's  power  to  combat  the  disease,  its  entire 
absence  being  an  ill-omen.  In  typhoid  fever,  malaria,  in- 
fluenza, and  acute  miliary  tuberculosis  the  leukocytes  are  not 
increased,  which  fact  may  at  times  be  of  some  diagnostic 
value.  Usually  it  is  the  poly  nuclear  variety  of  leukocyte 
which  is  increased.  Malignant  tumors,  especially  sarcomata, 
are  accompanied  by  an  increase  in  the  number  of  leukocytes 
— even  to  the  extent  of  fifty  thousand  per  cubic  millimetre  or 
more — the  small  mononuclear  being  the  variety  mainly  affected. 
In  syphilis,  rickets,  and  other  cachexias  there  may  be  a  similar 
leukocytosis.  There  is  also  an  increase  in  the  number  of 
leukocytes  after  hemorrhage. 

In  leukaemia  there  is  an  enormous  and  permanent  increase 
in  the  number  of  leukocytes — one  to  three  hundred  thousand 
per  cubic  millimetre  in  moderate  cases. 

Alterations  in  the  blood-plates  are  as  yet  but  little  under- 
stood. 

The  amount  of  haemoglobin  contained  in  each  red  globule 
varies  normally  with  the  size  of  the  corpuscle,  though  patho- 
logically this  relation  does  not  exist.  In  most  cases  the 
amount  of  haemoglobin  in  each  globule  is  diminished  ;  in  some 
cases,  however,  there  is  an  actual  increase  in  the  amount  of 


312  DISEASES  OF  THE  BLOOD. 

haemoglobin  per  red  corpuscle — ascertained  by  comparing  the 
number  of  red  cells  per  cubic  millimetre  with  the  percentage 
of  haemoglobin. 

THE   ANAEMIAS. 

The  term  anaemia  includes  a  variety  of  conditions  in  which 
there  are  qualitative  alterations  in  the  blood,  the  most  con- 
spicuous evidence  of  which,  clinically,  is  pallor  of  the  skin 
and  mucous  membranes,  due  to  a  reduction  in  the  amount  of 
haemoglobin,  whether  from  a  reduction  in  the  amount  of 
blood,  in  the  number  of  red  corpuscles,  or  in  the  coloring- 
matter  alone. 

Reduction  in  the  number  of  red  corpuscles — oligocythcemia, 
and  of  the  amount  of  haemoglobin — oligochromcemia,  are  usu- 
ally associated,  though  the  latter  may  be  present  without 
alteration  in  the  number  of  red  cells,  as  is  seen  especially  in 
chlorosis. 

The  anaemias  are  usually  divided  into  two  classes  clinically 
— the  primary  or  essential,  and  the  secondary  or  symptomatic. 

The  former  include  simple  primary  anaemia,  pernicious 
anaemia,  chlorosis,  leukaemia,  and  Hodgkin's  disease,  neither 
of  which  is  dependent  on  any  preceding  affection. 

The  latter  include  those  anaemias  produced  by  disturbances 
outside  of  the  haemopoietic  system — e.  g.,  tuberculosis,  malig- 
nant disease,  etc. 

Primary  Anaemias. 

Chlorosis  is  a  primary  anaemia,  occurring  principally  in  girls 
about  the  time  of  puberty,  characterized  by  an  excessive  reduc- 
tion in  the  amount  of  haemoglobin  and,  in  most  cases,  a  peculiar 
sallow  complexion  having  a  somewhat  greenish  tinge,  which 
has  won  for  it  the  term  green-sickness.  The  red  corpuscles  may 
be  normal  in  number,  but  generally  in  prolonged  cases  there 
is  a  considerable  reduction — never  so  great,  however,  as  the 
percentage-reduction  of  haemoglobin ;  in  other  words,  the 
amount  of  coloring-matter  in  each  individual  corpuscle — la 
valeur  globulaire — is  reduced.  This  difference  may  be  as 
great  as  30  per  cent. ;  while  the  number  of  corpuscles  in  a 
given  case  may  be  reduced  to  only  two  or  three  million  per 
cubic  millimetre,  the  quantity  of  haemoglobin  may  be  less 
than  20  or  30  per  cent,  of  normal. 


PRIMARY  ANAEMIAS.  313 

When  the  red  blood-corpuscles  are  reduced  in  number  they 
are  usually  more  or  less  altered  in  shape,  according  to  the 
degree  of  the  oligocythsemia.  Poikilocytes,  microcytes,  and 
polychromatophiles  are  frequently  present,  and,  when  the  con- 
dition is  very  severe,  megalocytes  may  be  quite  numerous; 
nucleated  red  blood-corpuscles — usually  normoblasts — are 
sometimes  seen.  The  number  and  variety  of  leukocytes  are 
normal  in  uncomplicated  cases. 

The  only  associated  organic  lesion  which  has  been  noted 
is  a  congenital  smallness  of  the  heart,  bloodvessels,  and 
genital  organs. 

Progressive  pernicious  anaemia  is  a  severe  anaemia  which  has 
no  apparent  cause  and  tends  uninterruptedly  toward  a  fatal 
issue.  The  number  of  red  blood-corpuscles  is  reduced  to  a 
greater  degree  than  in  any  other  condition,  sinking  below  five 
hundred  thousand  per  cubic  millimetre,  even  to  one  hundred 
and  forty-three  thousand  in  one  case  which  has  been  recorded. 

A  characteristic  feature  is  the  average  increase  in  size  of 
the  red  corpuscles.  Microcytes  may  occur,  but  are  not  com- 
mon. Erythroblasts,  poikilocytes,  and  polychromatophiles  are 
frequently  noted.  The  haemoglobin  is  always  reduced,  but 
never  to  the  same  extent  as  the  red  blood-corpuscles.  The 
leukocytes  undergo  no  important  change. 

In  some  cases  it  has  been  possible  to  assign  a  cause. 
Atrophy  of  the  gastro-intestinal  mucous  membrane  and  certain 
intestinal  parasites,  especially  the  anchylostoma  duodenale, 
produce  a  secondary  anaemia,  often  not  distinguishable  from 
progressive  pernicious  anaemia.  The  anaemia  is  usually  looked 
upon  as  resulting  from  the  excessive  destruction  of  blood 
rather  than  from  its  defective  formation.  The  pigmentation 
of  various  organs,  the  jaundice  often  present,  and  the  excess 
of  coloring-matter  in  the  urine  suggest  this  conception  of  its 
nature. 

The  various  viscera  are  pale  and  bloodless,  and  in  a  more  or 
less  advanced  stage  of  fatty  degeneration. 

A  simple  primary  anaemia  arising  without  any  apparent 
cause  is  not  recognized  by  many  writers,  yet  cases  do  occur  in 
which  the  characteristic  features  of  both  chlorosis  and  per- 


314  DISEASES  OF  THE  BLOOD. 

nicious  anaemia  are  absent.  The  red  blood-corpuscles  and 
haemoglobin  are  usually  reduced  to  the  same  degree  ;  the  leuko- 
cytes undergo  no  important  change  either  in  number  or  kind. 

Leukaemia  or  leukocythsemia :  The  term  leukaemia — white 
blood — was  first  proposed  by  Virchow7,  in  1845,  for  cases  in 
which  there  was  an  enormous  increase  in  the  number  of  leuko- 
cytes in  the  blood,  associated  with  enlargement  of  the  spleen 
and  lymphatic  glands.  The  condition  had  previously  been 
regarded  as  an  inflammation  or  suppuration  of  the  blood. 

The  disease  is  well  named,  for  at  times  the  blood  is  so 
white  it  resembles  milk  or  pus.  The  older  writers  were 
accustomed  to  speak  of  the  relations  existing  between  the 
number  of  white  and  red  corpuscles ;  but  as  this  depends  also 
on  fluctuations  in  the  number  of  red  corpuscles,  it  is  more  im- 
portant to  know  the  exact  number  of  leukocytes  per  cubic 
millimetre.  Instead  of  one  leukocyte  to  five  or  six  hundred 
red  cells,  the  proportion  is  frequently  one  to  eight,  even  one 
to  two  or  three ;  in  cases  of  moderate  severity  there  are  one 
to  three  hundred  thousand  per  cubic  millimetre — five  hundred 
thousand  per  cubic  millimetre  not  being  infrequent. 

Yet  it  is  not  so  much  the  number  of  leukocytes,  which  is 
characteristic  of  this  disease,  as  the  character  of  the  predomi- 
nant variety ;  for  the  proportion  of  one  to  eight  has  been 
noted  in  non-leukaemic  anaemias,  and  in  some  cases  of  leuko- 
cytosis  there  may  be  as  many  as  one  hundred  thousand  white 
blood-corpuscles  per  cubic  millimetre. 

Virchow  recognized  two  forms  of  the  disease,  one  character- 
ized by  enlargement  of  the  spleen,  in  which  the  blood  showed 
an  excessive  number  of  large  white  cells ;  and  another  charac- 
terized by  enlargement  of  the  lymphatic  glands,  in  which  the 
small  variety  of  leukocyte  predominated. 

A  third  form  of  the  disease  was  later  described  by  Neu- 
mann, in  which  there  were  marked  changes  in  the  marrow  of 
the  bones. 

Though  it  is  customary  to  speak  of  lymphatic,  splenic,  and 
myelogenous  varieties  of  the  disease,  these  different  forms  are 
often  associated.  There  is  some  doubt  as  to  a  pure  splenic 
variety  existing  without  accompanying  changes  in  the  bone- 
marrow. 


LEUKEMIA   OR  LEUKOCYTHJEMIA.  315 

The  spleno-medullary  variety  of  leukaemia  is  especially  recog- 
nized by  the  presence  in  the  blood  of  numbers  of  large-sized 
leukocytes,  which  have  been  called  myelocytes  on  account  of 
their  supposed  origin  in  bone-marrow.  These  cells  are  rarely 
if  ever  seen  in  normal  blood  ;  they  are  usually  1  Q/JL  to  20/j  in 
diameter,  though  occasionally  not  much  larger  than  a  red 
corpuscle,  when  they  can  only  be  distinguished  from  the 
mononuclear  leukocytes  by  the  presence  of  neutrophilic  gran- 
ules in  their  protoplasm,  or  sometimes  of  eosinophilic  granules 
— eosinophile  myelocytes.  When  the  blood  is  stained  with 
haematoxylin  and  eosin  these  neutrophilic  granules  cannot  be 
seen  ;  but  if  Ehrlich's  triple  stain  is  employed  they  are  readily 
recognized.  In  this  variety  of  leukaemia  the  myelocytes  often 
make  up  30  to  50  per  cent,  of  the  total  number  of  leuko- 
cytes, while  in  other  diseases  in  which  they  rarely  occur  they 
never  exceed  2  to  9  per  cent. 

The  relative  number  of  eosinophiles — normally  constituting 
2  to  4  per  cent,  of  the  white  blood-cells — is  not  usually  in- 
creased, though  there  is  always  an  absolute  increase  in  their 
number — 50  to  80  per  cent,  of  which  are  eosinophile  mye- 
locytes. It  was  formerly  supposed  that  a  relative  increase 
in  the  eosinophiles  was  diagnostic  of  leukaemia ;  they  are  in- 
creased to  a  much  greater  extent,  however,  in  some  other 
affections — notably  in  asthma  and  diseases  of  the  skin — and 
often  are  even  diminished  in  leukaemia.  The  number  of  poly- 
nuclear  neutrophiles  is  relatively  diminished,  making  up  but  50 
per  cent. — in  some  cases  even  less  than  10  per  cent,  of  the  total 
number  of  white  blood-cells ;  an  increase  would  suggest  some 
inflammatory  complication.  The  small  lymphocytes  are  also 
relatively  reduced  in  number,  constituting  but  3  to  5  per  cent., 
instead  of  15  to  25  per  cent,  of  the  total  number  of  leukocytes. 

Basophilic  myelocytes  and  small  leukocytes  are  occasionally 
noted,  their  protoplasm  containing  granules  which  have  a 
selective  affinity  for  basic  dyes. 

The  red  blood-corpuscles  are  usually  reduced  to  two  or  three 
million  per  cubic  millimetre,  and  proportionally  likewise 
the  haemoglobin.  Alterations  in  the  size,  shape,  and  stain- 
ing properties  of  the  red  cells  may  be  noted  ;  and  erythro- 
blasts  are  always  found  at  some  stage  of  the  disease — 
mostly  normoblasts,  though  some  megaloblasts  and  micro- 


316  DISEASES  OF  THE  BLOOD. 

blasts.  The  presence  of  these  nucleated  red  blood-cells  is 
especially  characteristic  when  the  oligocythsemia  is  slight- 
in  fact,  it  is  the  only  disease  in  which  they  are  present  under 
that  condition.  The  manner  in  which  this  excessive  accumula- 
tion of  leukocytes  is  brought  about,  whether  due  to  an  increased 
proliferation  or  a  diminished  destruction  of  these  elements,  is 
not  known.  Some  maintain  that  it  is  primarily  a  disease  of 
the  blood-making  organs — the  spleen,  lymphatic  glands,  and 
bone-marrow — while  others  believe  the  changes  in  these 
organs  to  be  secondary  to  the  alterations  in  the  blood.  The 
enlargement  of  the  spleen,  which  is  nearly  always  present,  is 
the  result  of  an  enormous  increase  of  the  lymphatic  elements. 
The  marrow  of  spongy  and  long  bones  becomes  yellowish  in 
color;  microscopically  the  marrow-cells  are  found  to  be 
greatly  increased  in  number.  The  lymphatic  glands  are  also 
sometimes  involved  ;  in  fact,  any  lymphatic  tissue  in  the  body 
may  be  affected. 

In  the  lymphatic  variety  of  leukaemia,  which  is  of  much 
less  frequent  occurrence,  the  enlargement  of  the  lymphatic 
glands  is  especially  marked.  A  pure  lymphatic  form  is  rare, 
usually  there  being  some  involvement  of  the  spleen  and  bone- 
marrow.  The  leukocytes  are  never  increased  to  the  same 
extent,  the  large  and  small  mononuclear  elements  making  up 
95  per  cent,  of  their  number.  Myelocytes  are  present  in  very 
small  numbers  only,  if  at  all ;  the  eosinophiles  and  polynu- 
clear  neutrophiles  are  relatively  and  absolutely  reduced. 

The  oligocythaBmia  is  much  more  marked  than  in  the  spleno- 
myelogenous  variety ;  nucleated  red  blood-corpuscles,  how- 
ever, are  extremely  infrequent. 

Hodgkin's  disease,  malignant  lymphoma,  lymphosarcoma ,  or 
pseudoleukcemia,  resembles  leukaemia  in  all  respects  except  in 
that  there  is  no  increase  in  the  number  of  leukocytes  in  the 
blood.  The  lymphatic  glands  throughout  the  body  are 
enlarged  as  a  result  of  a  hyperplastic  proliferation  of  the  lym- 
phatic elements.  As  in  leukaemia,  the  spleen,  bone-marrow, 
tonsils,  lymphatic  follicles  of  the  intestinal  mucous  membrane, 
and  all  the  other  lymphatic  tissues  in  the  body  may  be  affected. 
Nodules,  from  the  size  of  millet-seed  to  that  of  a  walnut, 
composed  of  lymphoid  cells,  may  occur  in  the  liver,  kidneys, 


SECONDARY  ANAEMIAS.  317 

lungs  and  serous  membranes ;  also,  rarely,  in  the  ovaries,  tes- 
ticles, heart,  and  brain. 

At  the  beginning  of  the  disease  the  blood  is  found  to  be 
normal,  but  soon  the  anaemia  and  cachexia  become  prominent. 
When  the  anemia  is  pronounced,  alterations  in  the  size  and 
shape  of  the  red  blood-corpuscles  occur,  and  a  few  nucleated 
erythrocytes — usually  normoblasts — may  be  noted,  as  in  other 
severe  anaemias. 

The  percentage-reduction  in  hemoglobin  is  often  greater 
than  that  of  the  red  corpuscles — a  so-called  chlorotic  con- 
dition of  the  blood. 

Cases  are  sometimes  observed  in  which  the  spleen  alone  is 
involved,  and  are  described  under  the  term  splenic  anemia. 

Secondary  Anaemias. 

Whatever  the  cause  of  secondary  or  symptomatic  anaemias, 
they  have  certain  common  characteristics.  There  is  usually 
a  greater  percentage- reduction  of  hemoglobin  than  of  red 
blood-corpuscles ;  in  mild  cases  the  number  of  red  cells  is  not 
reduced,  though  the  haemoglobin  varies  from  60  to  75  per  cent, 
of  normal.  The  individual  corpuscular  richness  in  hemo- 
globin is  never  above  par,  as  in  pernicious  anemia.  In  severe 
cases  the  oligocythemia  may  be  almost  as  great  as  in  the  latter 
disease.  Alterations  in  the  size  and  form  of  the  red  cells 
occur ;  microcytes  and  megalocytes  are  sometimes  noted,  the 
former  more  frequently,  however. 

Poikilocytosis  and  degenerative  changes — vacuolation  and 
polychromatophilia — occur  in  the  red  blood-corpuscles;  nor- 
moblasts, the  presence  of  which  may  be  regarded  as  evidence 
of  a  regenerative  effort  on  the  part  of  the  blood-making  organs, 
are  likewise  to  be  seen. 

The  number  of  leukocytes  varies  considerably ;  if  there  is 
a  leukocytosis,  it  consists  of  an  increase  in  the  polynuclear 
neutrophiles. 


CHAPTER    IV. 


DISEASES  OF  THE  CIRCULATORY  SYSTEM. 


FIG.  137. 


HEART  AND  PERICARDIUM. 

ATROPHY. 

Hypoplasia  of  the  heart — a  congenital  smallness — is  often 
associated  with  a  similar  malformation  of  the  aorta  and  other 
bloodvessels,  and  of  the  generative  organs.  This  condition 
has  been  noted  especially  in  connection  with  chlorosis.  The 
heart  is  uniformly  affected  in  all  its  parts. 

Brown  atrophy,  an  acquired  change  associated  with  pigmen- 
tation, is  seen  in  cases  of  wasting  diseases,  as  tuberculosis  and 

cancer ;  and  especially  also  in  old 
age.  The  heart  is  dark  brown  in 
color,  and  quite  small,  often  not 
weighing  more  than  a  third  of 
normal ;  its  walls  are  thin  and 
cavities  contracted.  The  epicar- 
dium  is  frequently  wrinkled,  the 
coronary  arteries  prominent  and 
tortuous,  due  to  the  loss  of  subperi- 
cardial  fat.  On  microscopical 
section  the  muscle-fibres  are  found 
to  be  thinner  than  normal,  and  in 
the  centre  of  each  is  a  brown  spot 
of  pigment  (Fig.  137).  Similar 
pigmentation  is  also  often  asso- 
ciated with  cardiac  hypertrophy. 
The  resulting  symptoms  are  not 
usually  serious,  as  the  lessened 
power  of  the  cardiac  muscle  is  but  commensurate  with  the 
decreased  demand  made  upon  it, 

318 


Brown  or  senile  atrophy  of  the 
heart  (Ribbert).  The  muscle- 
fibres  are  reduced  in  diameter; 
at  the  ends  of  the  nuclei  are  col- 
lections of  pigment-granules. 


HYPERTROPHY. 


319 


HYPERTROPHY. 

Three  varieties  of  cardiac  hypertrophy  are  usually  described, 
according  to  the  size  of  the  cavities  associated  with  the 
increased  thickness  in  the  muscle-walls;  simple,  in  which  the 
cavities  are  of  normal  size ;  concentric,  in  which  they  are 
smaller  than  normal ;  and  eccentric,  in  which  they  are  dilated. 
In  x'nnple  dilatation  also  the  heart  is  enlarged,  but  not  hyper- 
trophied. 

Causes :  The  hypertrophy  is  the  result  of  increased  demands 
made  upon  the  heart-muscle.  Stenotic  and  incompetent  valves 
are  a  very  frequent  cause.  General  arterio-sclerosis,  often 


--LV 


Hypertrophy  of  left  ventricle  (front  view).  Heart  is  elongated.  Septum  occupies 
middle  of  anterior  surface.  (From  a  case  of  granular  kidney  from  a  specimen 
in  Charing  Cross  Hospital  Museum  (Green).) 

associated  with  interstitial  nephritis,  greatly  increases  the  work 
of  the  left  ventricle  and  leads  to  its  hypertrophy  (Figs.  138 
and  139).  Obstruction  to  the  pulmonary  circulation,  as,  for 
instance,  in  fibroid  phthisis  and  emphysema,  leads  to  hyper- 
trophy of  the  right  ventricle  (Figs.  140  and  141).  Simple 
functional  overactivity,  as  in  hysteria  and  exophthalmic  goitre, 
may  lead  to  a  uniform  hypertrophy  of  the  whole  heart. 

Dilatation  occurs  where  the  heart-muscle  is  exhausted  and 
unable  to  overcome  the  impediment. 

Microscopically  is  noted  an  increase  in  the  size  of  the 
muscle-fibres ;  there  is  also  probably  an  increase  in  their 


320 


DISEASES  OF  THE  CIRCULATORY  SYSTEM. 


number.     Fibroid  and  fatty  degenerative  changes  are  usually 
associated  with  dilatation.     The  size  and  weight  of  the  organ 


A — 


RA 


•~LV 


RV 


Hypertrophy  of  right  ventricle  (front  view).  Heart  is  quadrilateral  and  septum  is 
displaced  to  the  left.  Right  auricle  is  dilated.  (From  a  case  of  chronic  bron- 
chitis and  emphysema;  specimen  in  Charing  Cross  Hospital  Museum  (Green).) 


LA 


FIG.  141. 


-RV 


LV- 


Anterior  half  of  heart  (Fig.  138),  seen 
from  behind.  Left  ventricle  forms 
the  whole  of  apex.  Wall  of  LV : 
wall  of  RV: :  10 :  2  (normal  pro- 
portion, 5 : 2)  (Green). 


RA 


Anterior  half  of  heart  (Fig.  139),  seen 
from  behind.  Right  ventricle  is  seen 
to  take  greater  share  in  formation  of 
apex  than  left  ventricle  does.  Wall  of 
RV  is  much  thickened,  but  not  so 
thick  as  that  of  the  left.  Tricuspid 
orifice  and  RA  are  dilated  (Green). 


FATTY  INFILTRATION.  321 

are  often  so  greatly  increased  as  to  justify  the  term  "  cor  bovi- 
nuni".  As  long  as  the  hypertrophy  is  compensatory  there  are 
no  symptoms ;  but  when  the  cardiac  muscle  can  no  longer 
meet  the  demands  made  upon  it,  the  results  are  most  serious. 
If  the  left  ventricle  is  at  fault,  there  is  a  passive  congestion 
of  the  pulmonary  circulation.  When  the  right  ventricle  is 
at  fault,  or  in  turn  becomes  involved,  there  occur  passive  con- 
gestion of  the  general  systemic  circulation  and  dropsy. 


DEGENERATIVE  CHANGES. 

Cloudy  Swelling. 

Cloudy  swelling  occurs  either  as  an  early  stage  of  inflamma- 
tion or  as  a  precursor  of  fatty  degeneration.  It  is  noted 
especially  in  the  course  of  diphtheria,  smallpox,  scarlet  fever, 
and  other  infectious  diseases;  also  in  rheumatism  and  after 
severe  burns. 

The  myocardium  is  soft — even  friable,  pale,  and  looks  as 
if  it  had  been  slightly  boiled. 

Microscopically  the  muscle-fibres  are  seen  to  be  swollen — the 
spaces  between  the  individual  muscle-fibres  being  smaller  than 
normal — and  their  transverse  striations  are  indistinct.  The 
fibres  appear  as  though  seen  through  ground  glass  or  a  layer 
of  dust,  due  to  the  presence  of  innumerable  fine  albuminous 
granules. 

Fatty  Infiltration. 

Normally  there  is  a  certain  amount  of  adipose  tissue  beneath 
the  epicardium,  especially  along  the  course  of  the  coronary 
arteries,  lower  border  of  the  left  ventricle,  and  at  the  apex. 

Pathologically  the  adipose  tissue  may  not  only  form  a  thick 
coating  over  the  entire  surface,  but  even  extend  into  the  walls 
of  the  heart  between  the  muscle-fibres,  deposits  even  appear- 
ing at  places  under  the  endocardium.  The  muscle-fibres 
themselves  are  not  involved,  except  that  they  are  often 
atrophied  as  the  result  of  pressure,  when  the  accumulation  of 
adipose  tissue  is  excessive.  Besides  the  cardiac  weakness  thus 
resulting,  a  fatty  degeneration  of  the  muscle-fibres  may  be 
induced. 

21— Hist. 


322         DISEASES  OF  THE  CIRCULATORY  SYSTEM. 


Fatty  Degeneration. 

In  fatty  degeneration  the  individual  muscle-fibres  are  in- 
volved, the  cell-protoplasm  being  replaced  to  a  great  extent  by 
small  globules  of  fat.  These  droplets  appear  first  in  the 
neighborhood  of  the  nucleus  ;  but  may  finally  occupy  the 
whole  fibre,  giving  rise  to  an  appearance  somewhat  resembling 
cloudy  swelling;  the  granules  are  larger  than  in  the  latter 
condition,  however,  dissolve  in  alcohol,  chloroform,  or  ether, 
and  stain  black  with  osmic  acid  (Fig.  142).  The  main  factor 

FIG.  142. 


Mmm? 

W:  PflP'IV'f  ^;v;'!^ilu^ 
fc;llli:l|l^;ipil!i 

/  *     *   ,  •  /   t ,..  •( 

WRi*** 


. 


Well-marked  chronic  fatty  degeneration  of  heart,  a,  healthy  ;  b,  fatty  degeneration 
of  muscle-fibres.    X  80  (Ziegler). 

in  its  production  is  either  a  general  or  a  local  anaemia.  The 
local  anaemia  may  be  brought  about  by  sclerosis  of  the  coro- 
nary arteries,  or  an  improper  circulation  of  the  blood  through 
them  as  the  result  of  a  valvular  lesion.  The  condition  is 


MYOCARDITIS.  323 

frequently  associated  with  pernicious  anemia,  leukaemia, 
phthisis  and  other  wasting  diseases ;  and  with  arsenic-  and 
phosphorus-poisoning. 

The  macroscopic  appearance  of  the  heart  is  quite  character- 
istic. It  is  usually  pale,  flabby,  and  dilated.  The  degene- 
rative change  generally  occurs  in  patches,  the  matted  appear- 
ance produced  thereby  being  most  readily  seen  from  within, 
beneath  the  endocardium.  When  the  process  is  diffuse  the 
cardiac  muscle  has  a  uniform  yellowish  hue. 

Myomalacia  cordis  is  a  localized  softening — a  necrosis — of 
the  heart-wall  due  to  embolic  or  thrombotic  obstruction  of  the 
coronary  arteries.  The  area  from  which  the  blood  is  cut  off 
is  often  wedge-shaped,  pale  yellow  in  color,  and  depressed 
below  the  surface. 

Amyloid  and  hyaline  degenerations  are  sometimes  noted. 
Calcareous  infiltration  of  the  myocardium  occurs,  but  is  ex- 
tremely rare. 

INFLAMMATIONS. 

Myocarditis. 

Inflammation  of  the  heart-muscle  may  be  primary,  but  is 
much  more  frequently  secondary  to  a  peri-  or  endocarditis. 
It  occurs  in  the  course  of  acute  infectious  fevers,  as  typhoid, 
diphtheria,  scarlet  fever,  smallpox,  and  puerperal  septicaemia. 
The  heart-muscle  is  friable  and  has  a  yellowish-red  and 
matted  appearance  ;  the  cavities  are  usually  dilated.  Micro- 
scopically, there  is  noted  in  addition  to  the  cloudy  swelling 
of  the  muscle-fibres  a  round-celled  infiltration  of  the  sup- 
porting connective-tissue  framework  ;  some  are  proliferated 
connective-tissue  cells,  the  majority,  however,  being  migrated 
leukocytes.  Abscesses,  appearing  macroscopically  on  section 
of  the  heart-wall  as  yellowish-white  spots,  may  occur.  They 
are  most  frequent  in  the  anterior  wall  of  the  left  ventricle,  and 
vary  from  the  size  of  a  pinhead  to  that  of  a  cherry. 

In  fibrous  or  chronic  myocarditis  there  is  a  great  increase  in 
the  interstitial  connective  tissue.  This  fibroid  change  -or 
substitution  may  be  diffuse  or  circumscribed.  Diffuse  inter- 
muscular  sclerosis  is  often  associated  with  general  arterio- 


324         DISEASES  OF  THE  CIRCULATORY  SYSTEM. 


sclerosis  and  fibroid  change  in  the  kidneys  and  other  organs. 
As  a  result,  the  heart  may  be  hypertrophied  by  the  increased 
work  imposed  upon  it,  but  much  more  frequently  the  muscle- 
fibres  are  atrophied  by  the  mechanical  pressure  of  the  newly 
formed  fibrous  tissue,  and  are  found  to  have  undergone 
granular  and  fatty  degeneration.  Circumscribed  areas  of 
fibroid  substitution  are  often  consecutive  to  degenerative 
changes  produced  by  obstruction  of  the  coronary  arteries.  A 
saccular  dilatation — aneurism — may  result  from  the  thinned 
heart-wall  giving  way  to  pressure  from  within  at  such  a 
point. 

Endocarditis. 

Inflammation  of  the  endocardium  usually  aifects  the  valves ; 
when  affecting  the  cavities  of  the  heart  it  may  be  designated 
specially  as  mural  endocarditis. 

Acute  endocarditis  is  rarely  a  primary  affection.  The  most 
frequent  cause  is  acute  articular  rheumatism.  It  occurs  also 


FIG.  143. 


FIG.  144. 


Inflammation  of  aortic  valves,  the  ear- 
lier stage  of  the  process,  showing  the 
situation  of  the  inflammatory  gran- 
ulations (Green). 


Inflammation  of  mitral  valve,  the  ear- 
lier stage  of  the  process.  Valve  seen 
from  the  auricular  surface,  showing 
the  situation  of  the  inflammatory 
granulations  (Green). 


in  the  course  of  pneumonia,  puerperal  septicaemia,  scarlet  fever, 
typhoid  fever,  gonorrhoea,  and,  in  fact,  in  any  acute  infectious 
disease.  It  occurs  also  in  Bright's  disease,  cancer,  and  diabetes. 
The  most  characteristic  lesions  are  the  so-called  warty 
vegetations  formed  along  the  line  of  contact  of  the  valves, 
especially  on  the  auricular  aspect  of  the  mitral,  and  in  a  row 


CHRONIC  ENDOCARDITIS.  325 

of  bead-like  elevations  on  the  ventricular  surface,  some  little 
distance  from  the  margins  of  the  cusps  of  the  aortic  (Figs. 
143  and  144).  These  small  warty  elevations  are  less  fre- 
quently seen  on  the  tricuspid  and  pulmonary  valves,  and  on 
the  chordae  tendinese  and  parts  of  the  mural  endocardium. 
They  crumble  and  can  be  easily  detached  by  the  finger, 
leaving  behind  a  slightly  roughened  surface,  or  possibly  a 
small  ulcer  the  size  of  the  base  of  the  vegetation.  The  change 
in  the  endocardium  produced  by  the  inflammatory  process 
and  the  extra  irritation  and  friction  at  the  line  of  contact  of 
the  valves  on  closure,  invite  the  deposition  of  fibrin  ;  there 
is  an  active  proliferation  of  the  endothelial  cells,  which, 
together  with  migrating  leukocytes,  infiltrate  the  layers  of 
fibrin  and  tend  to  bring  about  the  organization  of  the  clot 
which  has  formed. 

In  some  cases  the  inflammatory  process  is  especially  severe 
and  there  is  a  tendency  to  suppuration  and  ulceration.  Small 
collections  of  pus  may  be  seen  at  the  base  of  the  valves.  The 
masses  of  fibrinous  deposit  are  more  abundant  and  irregular, 
occurring  indiscriminately  over  the  endocardial  surface  of  the 
valves  and  heart-wall.  Where  there  has  been  actual  destruc- 
tion of  tissue  there  will  be  noted  on  section,  microscopically, 
at  the  bases  of  these  vegetations,  typical  granulation-tissue, 
to  which  the  clot  is  firmly  adherent.  If  the  section  is  prop- 
erly stained,  micro-organisms  may  usually  be  seen  in  the 
superficial  layers  of  the  endocardium.  The  vegetations  are 
liable  to  be  broken  off  and  carried  in  the  circulation,  as  emboli, 
to  distant  parts.  If  the  micro-organisms  are  likewise  trans- 
ported, metastatic  abscesses  in  various  organs  are  produced. 

Chronic  endocarditis  results  in  various  distortions  of  the  af- 
fected leaflets  of  the  valves,  and,  in  consequence,  serious  dis- 
turbances in  the  circulation.  The  vegetations  become  fibrous 
and  have  a  broad  base.  As  in  all  chronic  inflammations,  there 
is  a  tendency  toward  the  overproduction  of  connective  tissue. 
The  proliferating  endothelial  and  connective-tissue  cells  and 
infiltrating  leukocytes  become  organized  into  fibrous  tissue. 
The  valves  are  thickened,  rigid,  and  eventually  retracted  and 
distorted.  The  opposed  inflamed  leaflets  of  the  valve  may 
become  agglutinated  or  firmly  adherent  to  the  adjacent  heart- 
wall  and  cause  still  further  deformity.  The  chordae  tendinese 


326         DISEASES  OF  THE  CIRCULATORY  SYSTEM. 

also  become  thick  and  rigid,  and  interfere  with  the  function  of 
the  valves.  The  dense  cicatricial  connective  tissue  may  be- 
come infiltrated  with  lime  salts. 

In  some  cases  the  inflammatory  process  may  be  chronic 
from  the  first.  This  is  especially  liable  to  occur  in  persons  of 
advanced  years,  and  also  in  connection  with  chronic  alcoholism, 
syphilis,  and  gout,  which  are  active  factors  also  in  producing 
general  arterio-sclerosis.  The  alterations  in  the  valves  lead  to 
stenosis,  an  obstruction  to  the  flow  of  blood  ;  or  insufficiency, 
when  the  valves  cannot  close,  and  thus  prevent  the  regurgita- 
tion  of  the  blood.  A  valve  may  be  both  stenotic  and  insuf- 
ficient. 

Either  condition  necessarily  leads  to  imperfect  circulation 
of  the  blood  through  the  heart.  The  natural  result  of  the  in- 
creased work  thrown  upon  the  heart-muscle  is  hypertrophy. 
When  this  compensatory  hypertrophy  fails,  most  serious 
changes  occur  in  the  various  organs.  The  lungs  become 
cedematous  and  gradually  indurated,  as  the  result  of  an  in- 
creased proliferation  of  the  interstitial  connective  tissue.  The 
pulmonary  vessels  are  distended,  even  varicose ;  thrombi  may 
form,  as  the  result  of  the  sluggish  circulation.  The  liver, 
spleen  and  kidneys  are  enlarged  by  reason  of  their  passive 
congestion.  The  countenance  becomes  cyanosed  from  the 
stagnation  of  the  circulation  and  lessened  oxidation  ;  there 
are  serous  effusions  into  the  peritoneal,  pleural,  and  pericardial 
sacs  and  general  oedema  of  the  subcutaneous  tissue  and  skin. 
The  mucous  membrane  of  the  gastro-intestinal  tract  is  swollen 
and  redematous. 

Pericarditis. 

Inflammation  of  the  pericardium  may  be  a  primary  affection, 
occurring  in  connection  with  rheumatism  and  Bright's  disease, 
and  various  acute  infectious  fevers,  as  pneumonia,  typhoid, 
scarlet  fever,  influenza,  and  puerperal  septicaemia;  or  much 
less  frequently  it  may  be  a  secondary  affection  resulting  from 
the  extension  of  an  inflammatory  process  from  neighboring 
structures  to  the  pericardium. 

The  membrane  first  becomes  dull  and  lustreless.  The 
character  of  the  exudate  varies,  usually  purely  serous,  but 
sometimes  hemorrhagic  or  seropurulent.  The  opposed  sur- 


ARTERITIS.  327 

faces  of  pericardium  often  look  as  if  the  two  layers  had  rubbed 
together,  while  the  more  or  less  marked  deposit  of  fibrin  was 
still  in  a  soft  plastic  condition,  giving  them  a  rough,  ragged, 
or  hairy  appearance,  suggesting  the  term  "cor  villosum." 

The  parietal  and  visceral  layers  may  become  agglutinated, 
constituting  what  is  known  as  adherent  pericardium,  which 
may  lead  to  hypertrophy  of  the  heart,  by  reason  of  the  in- 
creased work  thus  imposed  upon  it. 

Sclerotic  areas,  known  as  white  spots,  or  milk-spots,  are 
probably  the  result  of  a  chronic  localized  inflammation  ;  they 
are  noted  in  about  50  per  cent,  of  all  post-mortems.  They 
may  be  quite  small,  or  large  enough  to  cover  the  anterior  sur- 
face of  the  heart.  They  occur  most  frequently  on  the  right 
ventricle,  next  on  the  left  ventricle,  near  the  apex,  and  also 
on  the  posterior  surface  of  the  heart,  near  its  base.  They  are 
formed  simply  of  dense  connective  tissue,  covered  by  endothe- 
lium.  Their  exact  significance  is  not  fully  understood. 

THE  BLOODVESSELS. 

DEGENERATIONS. 

Fatty  degeneration :  Not  infrequently  there  are  seen  in  the 
aorta  and  other  parts  of  the  arterial  system  yellow  spots  or 
streaks  slightly  raised  above  the  internal  surface ;  under  the 
microscope  it  is  found  that  the  endothelial  cells  of  the  intima 
have  undergone  fatty  degeneration.  The  degeneration  may 
involve  also  the  muscle-cells  of  the  media.  The  affected  areas 
may  soften  and  small  superficial  erosions  result. 

Calcareous  infiltration  most  frequently  affects  the  middle 
coat  of  the  artery,  occurring  by  preference  in  vessels  of  me- 
dium size.  The  greatly  increased  rigidity  of  the  radials,  often 
noted  clinically,  is  generally  due  to  this  cause. 

Amyloid  degeneration  usually  begins  in  the  capillary  walls 
of  the  organ  affected.  The  entire  wall  is  involved. 

ARTERITIS. 

Acute  inflammation  of  the  walls  of  an  avtery,  independent  of 
any  neighboring  inflammatory  process,  is  very  rare. 


328         DISEASES  OF  THE  CIRCULATORY  SYSTEM. 

Chronic  arteritis,  atheroma,  or  arterio-sclerosis,  however,  is 
of  frequent  occurrence.  The  aorta  alone  may  be  affected,  but 
more  commonly  the  whole  arterial  system  is  more  or  less  uni- 
formly involved ;  the  veins  even  may  be  involved  ("angio- 
sclerosis  ").  It  is  usually  associated  with  sclerotic  changes  in 
the  heart  and  internal  organs,  and  seems  to  be  dependent  upon 
the  same  causes — syphilis,  gout,  rheumatism,  lead-poisoning, 
chronic  alcoholism,  Bright's  disease,  and  old  age.  It  some- 
times follows  acute  infections,  as  typhoid  and  scarlet  fever, 
and  occasionally  seems  to  be  dependent  on  the  cachexia  of 
cancer  and  tuberculosis. 

In  the  aorta  at  an  early  stage  of  the  process  there  are  pale 
pinkish,  rounded,  or  oval  patches  or  nodules  beneath  the 
smooth  and  unaltered  intima,  varying  in  size  from  a  mere 
point  to  half  an  inch  in  diameter.  On  cutting  into  one  of 
these  patches  it  is  found  to  be  firm  and  fibrous ;  in  the  centre 
there  may  be  a  yellow  focus  of  fatty  degeneration.  Micro- 
scopically the  patch  is  composed  of  dense  fibrous  tissue  which 
seems  to  have  been  produced  by  a  proliferation  of  the  subendo- 
thelial  connective-tissue  cells ;  at  first  many  round,  oval,  and 
stellate  cells  can  be  readily  seen,  but  later  the  structure  of  the 
affected  area  may  be  quite  indefinite  from  advancing  fatty 
degeneration.  The  calcareous  plates  often  met  with  in  the 
aorta  are  the  result  of  the  infiltration  of  such  patches  with 
the  salts  of  lime  ;  these  plates  may  be  so  numerous  as  to  alter 
completely  the  appearance  of  the  vessel. 

In  the  smaller  vessels  the  changes  are  somewhat  different. 
Similar  patches  of  opaque  and  firm  tissue,  one-sixth  to  one- 
third  of  an  inch  in  length,  may  occur  at  irregular  intervals 
along  the  course  of  the  vessels.  On  cross-section  of  the  artery 
its  lumen  is  seen  to  be  considerably  encroached  upon  at  one  side. 

In  other  cases — endarteritis  obliterans — these  patches  are  en- 
tirely absent ;  the  lumen  of  the  vessel  is  uniformly  encroached 
upon,  sometimes  almost  obliterated  by  the  increased  thickness 
of  the  intima  produced  by  an  active  proliferation  of  the  endo- 
thelial  and  subendothelial  connective-tissue  cells.  The  muscle- 
fibres  of  the  media  are  atrophied,  and  there  is  usually  a  marked 
thickening  of  the  adventitia,  the  result  of  a  round-celled  in- 
filtration which  becomes  more  or  less  fully  developed  into 
fibrous  tissue. 


ANEURISM.  329 

Serious  consequences  may  follow  these  changes  in  the  arterial 
walls.  In  the  coronary  arteries  the  obstruction  of  the  circu- 
lation may  be  the  immediate  cause  of  fatty  degeneration  of 
the  heart-muscle  and  death.  In  the  brain  the  anaemia  result- 
ing from  such  an  obstruction  may  result  in  areas  of  softening. 
In  the  aorta,  aneurismal  dilatation  is  a  frequent  result.  The 
heart  is  generally  hypertrophied  in  consequence  of  the  obstruc- 
tion to  the  circulation  offered  by  the  thickened  and  rigid 
arterial  walls. 

Aneurism. 

An  aneurism  (Fig.  145)  is  a  localized  dilatation  of  an  artery, 
resulting  from  any  cause  which  weakens  its  walls — as  arter- 
itis  and  injury,  and  from  increased  arterial  pressure.  Aneur- 
isms may  be  classified  according  to  their  shape  into  fusiform, 
cylindrical,  and  saccular. 

In  fusiform  and  cylindrical  aneurisms  there  is  a  general  dila- 
tation of  all  the  coats  of  the  artery.  A  cirsoid  aneurism  is  one 
in  which  the  vessel  is  rendered  tortuous  and  convoluted  as  the 
result  of  its  elongation  and  unequal  dilatation  of  different 
parts. 

In  sacculated  aneurisms,  the  most  important  variety,  there 
is  a  unilateral  dilatation  of  the  vessel.  First,  the  media  gives 
way,  and  then  there  is  a  dilatation  of  the  intima  and  adven- 
titia,  and  thus  is  formed  a  sac  which  communicates  writh  the 
artery  by  a  narrow  opening.  As  the  sac  increases  in  size  it 
may  finally  rupture.  The  blood  may  be  retained  subsequent 
to  rupture  by  the  surrounding  tissues  ;  the  term  false  aneurism 
is  used  to  designate  such  a  cavity,  communicating  with  an 
artery  and  containing  blood,  the  walls  of  which  are  not  formed 
by  the  coats  of  the  vessel.  A  dissecting  aneurism  is  one  in 
which  rupture  of  the  intima  occurs  and  the  blood  burrows  a 
false  passage  between  the  coats  of  the  artery. 

The  results  of  the  continued  presence  of  the  aneurism  may 
be  extensive  necrosis  of  neighboring  tissues.  Erosion  of  the 
vertebrae  and  pressure  of  the  aneurism  on  the  spinal  cord  have 
been  the  unsuspected  cause  of  a  paraplegia.  In  a  similar 
manner  the  sternum  and  ribs  may  be  eroded  and  the  aneurism 
project  beneath  the  skin. 


330        DISEASES  OF  THE  CIRCULATORY  SYSTEM. 

FIG.  145. 


Aneurism  of  the  ascending  aorta  (woman,  agred  30).  A,  aorta ;  B,  orifice  of  commu- 
nication ;  C,  aneurismal  sac;  D,  rib  adherent  to  the  sac;  E,  shrunken  aortic 
valves  (Ziegler). 

PHLEBITIS. 

Acute  inflammation  of  a  vein  occurs  either  in  connection 
with  the  formation  of  a  thrombus — thrombophlebitis,  or  is 
associated  with  an  inflammatory  process  in  surrounding  tis- 
sues, which  may  produce  thrombosis  also,  secondarily. 


PHLEBITIS.  331 

Chronic  phlebitis  may  occur  in  association  with  arterio- 
sclerosis, the  changes  being  of  the  same  character,  but  rarely 
so  marked.  Calcareous  infiltration  of  the  affected  areas  is 
much  less  common. 

Varix  is  a  dilatation  of  veins  analogous  to  the  aneurismal 
dilatation  of  arteries.  The  essential  factor  in  its  production 
is  an  increase  in  blood-pressure  within  the  veins,  as  by  passive 
hypersemia  due  to  heart  disease,  pressure  of  a  tumor  or  the 
gravid  uterus. 

The  veins  are  not  only  dilated  but  elongated,  and  thus 
become  tortuous  and  convoluted ;  the  circulation  through 
them  is  greatly  slowed,  and  it  is  not  infrequent  for  thrombosis 
to  occur  in  consequence. 


CHAPTER    Y. 

DISEASES  OF  THE  RESPIRATORY  ORGANS. 

THE  NASAL  PASSAGES. 

Acute  rhinitis,  or  coryza,  inflammation  of  the  mucous  mem- 
brane of  the  nose,  occurs  most  frequently  as  a  simple  "cold  in 
the  head  "  due  to  exposure  ;  it  may  also  accompany  influenza, 
measles,  typhoid  fever,  and  other  infectious  diseases.  Diph- 
theria may  primarily  involve,  or  extend  to,  the  nasal  passages. 
The  inflammatory  hypersemia  gives  rise  to  a  feeling  of  stuffi- 
ness in  the  nose,  and  the  subsequent  exudation  to  the  muco- 
purulent  discharge. 

Chronic  rhinitis  supervenes  as  the  result  of  repeated  acute 
attacks.  The  mucous  membrane  becomes  thickened  and  the 
nasal  passages  obstructed — hypertrophic  rhinitis.  Later  there 
may  be  complete  atrophy  of  the  mucous  membrane ;  in  such 
cases  there  is  usually  an  extremely  foetid,  purulent  discharge 
— atrophic  rhinitis  or  ozcena. 

Syphilis  may  affect  the  nose,  in  the  tertiary  stage,  in  the 
form  of  gummata,  beginning  in  the  mucous  membrane, 
periosteum,  or  perichondrium.  There  may  be  extensive  nice  ra- 
tion and  destruction  of  tissue,  resulting  in  serious  deformities. 

THE  LARYNX. 

Acute  inflammation  of  the  larynx — laryngitis — may  be  due 
to  exposure  to  cold  or  inhalation  of  irritating  vapors;  and 
accompanies  measles,  whooping-cough,  smallpox,  typhoid  fever, 
and  other  infectious  diseases.  In  some  cases  there  is  such  an 
oedematous  infiltration  of  the  loose  submucous  tissue  over 
the  aryepiglottic  folds  and  at  the  base  of  the  epiglottis  as 
to  give  rise  to  serious,  even  fatal,  obstruction. 

The  severe  inflammatory  process  excited  by  the  diphtheria 
bacillus  is  especially  characterized  by  an  exudate  rich  in 
fibrin,  which  coagulates  and  adheres  to  the  larynx  as  a  grayish 

332 


THE  BRONCHIAL   TUBES.  333 

or  yellowish  psendomembrane.  Microscopically  this  pseudo- 
membrane  is  found  to  consist  mainly  of  the  fibrillae  of  fibrin 
and  migrated  leukocytes. 

Chronic  laryngitis  may  follow  repeated  acute  attacks,  or  re- 
sult from  overuse  of  the  voice  ;  or  it  may  be  secondary  to  dis- 
eases of  the  nasopharynx.  The  mucous  membrane  is  thick- 
ened, due  mainly  to  an  increase  of  connective  tissue,  which  is 
characteristic  of  all  chronic  inflammations  ;  it  has  quite  fre- 
quently a  granular  appearance  as  a  result  of  enlargement  of 
the  racemose  glands  of  the  larynx,  and  often  there  are  super- 
ficial ulcerations  or  erosions. 

Tuberculosis  of  the  larynx  is  generally  secondary  to  pulmo- 
nary tuberculosis,  occurring  in  about  30  per  cent,  of  these 
cases.  The  mucous  membrane  is  thickened  from  the  presence 
of  characteristic  tubercles  or  a  diffuse  infiltration ;  to  this  suc- 
ceed caseation  and  ulceration,  which  may  result  in  destruction 
of  the  vocal  cords. 

Syphilis  also  may  cause  deep  infiltrations,  necrosis,  and 
ulceration  ;  secondarily  serious  deformities  may  arise  from 
contraction  of  the  newly  formed  connective  tissue. 

Papillomata  constitute  more  than  one-half  the  tumors  of  the 
larynx.  They  are  especially  common  in  people  whose  pro- 
fession requires  the  constant  use  of  the  voice.  They  grow 
most  frequently  from  the  squamous  epithelium  of  the  vocal 
cords. 

Epithelioma  is  the  variety  of  cancer  generally  met  in  the 
larynx.  It  appears  first  in  the  form  of  a  nodular  thickening 
of  the  mucous  membrane,  which  later  undergoes  ulceration. 

Sarcoma  of  the  larynx,  which  is  usually  of  the  spindle- 
celled  variety,  is  not  of  frequent  occurrence. 

The  Bronchial  Tubes. 

Acute  inflammation  of  the  bronchial  tubes — bronchitis — 
results  frequently  from  the  extension  of  a  simple  inflamma- 
tory process  in  the  upper  air-passages ;  it  is  also  almost  a 
constant  manifestation  of  certain  acute  infectious  diseases,  as 
typhoid  fever,  measles,  scarlet  fever,  whooping-cough,  and  in- 
fluenza. The  larger  and  medium-sized  bronchi  are  involved  ; 
in  children,  however,  the  terminal  bronchioles  and  surround- 


334 


DISEASES  OF  THE  RESPIRATORY  ORGANS. 


ing  lung  tissue,  are  specially  liable  to  be  affected,  constituting 
lobular  or  catarrhal  pneumonia. 

The  mucous  membrane  of  the  bronchi  is  intensely  red  and 
swollen.     Upon   the  character  of  the  inflammatory  exudate 


FIG.  146. 


Catarrhal  bronchitis,  a,  areolar  tissue  of  the  submucosa.  infiltrated  with  serum 
and  leukocytes  ;  6,  alveolus  of  a  mucous  gland,  infiltrated  at  the  periphery  by 
leukocytes.  The  epithelium  is  undergoing  colliquative  necrosis,  and  in  the 
centre  of  the  lumen  are  a  few  leukocytes  with  fibrin,  c,  c',  blood  vessels;  c',  shows 
an  infiltration  of  the  wall  by  emigrating  leukocytes ;  d,  muscularis  mucosse ; 
e,  subepithelial  areolar  tissue  of  the  mucous  membrane,  infiltrated  with  serum 
and  leukocytes;  /,  columnar  epithelium  of  the  surface  in  a  state  of  colliquative 
necrosis  :  g,  exudate  within  the  bronchus.  In  this  portion  of  the  bronchus  the 
destructive  processes  are  so  acute  that  the  epithelium  is  destroyed,  instead  of 
stimulated  to  the  production  of  excessive  mucus  (Dunham). 

depends  the  appearance  of  the  sputum.  At  first  it  is  a  glairy, 
tenacious  fluid  containing  a  few  leukocytes — simply  an  exag- 
geration of  the  normal  secretion  of  the  glands  of  the  mucous 
membrane.  Later  it  becomes  yellowish  in  color,  muco- 


FIBRINOUS  BRONCHITIS.  335 

purulent  or  purulent,  and  less  tenacious,  histologically  resemb- 
ling pus  by  reason  of  the  large  number  of  leukocytes  present. 
When  the  amount  of  this  secretion  is  excessive,  especially  in 
more  chronic  cases,  the  condition  is  known  as  bronchorrhoea  ; 
in  some  instances  the  odor  of  the  sputum  is  very  offensive — 
foetid  bronchitis. 

Microscopically  the  bloodvessels  are  found  to  be  dilated,  and 
surrounding  them  and  infiltrating  the  walls  of  the  bronchi  are 
numerous  migrated  leukocytes  and  young  connective-tissue 
cells.  The  epithelial  cells  of  the  mucosa  are  degenerated  and 
in  many  places  desquamated  (Fig.  146). 

Chronic  bronchitis  occurs  most  commonly  in  the  aged,  who 
are  often  predisposed  by  reason  of  a  passive  congestion  of  the 
lungs,  due  to  some  form  of  cardiac  weakness.  It  may  follow 
a  neglected  acute  attack  or  gradually  develop  after  repeated 
subacute  attacks.  It  is  also  frequently  associated  with 
emphysema  or  other  diseases  of  the  lungs,  with  gout  and 
Bright's  disease,  and,  in  children,  with  rickets. 

The  bronchial  walls  are  usually  greatly  thickened  from  new 
connective-tissue  formation  in  the  outer  fibrous  coat.  The 
mucous  membrane  is  generally  atrophied ;  the  epithelial  cells 
are  no  longer  columnar,  but  rounded  or  polygonal.  In  some 
cases,  however,  the  mucous  membrane  is  swollen  and  hyper- 
femic,  and  dotted  with  little  gray  points — the  mucous  glands, 
which  are  greatly  enlarged. 

The  cartilages  of  the  bronchi  and  the  muscular  coat  may  be 
so  far  supplanted  by  newly  forming  connective  tissue  as  greatly 
to  weaken  their  walls.  This  in  connection  with  increased 
pressure  from  within,  due  to  the  increased  expiratory  efforts 
of  coughing,  may  cause  fusiform  or  saccular  dilatation  of  the 
bronchi  in  places,  bronchiectasis. 

Fibrinous  bronchitis  is  a  variety  of  chronic  bronchitis  in 
which  there  are  expectorated  at  intervals,  during  months  or 
years,  branching  fibrinous  casts  of  the  bronchi  of  a  lobe.  The 
exact  pathology  of  the  affection  is  not  understood.  Similar 
casts  of  the  larger  tubes  may  result  from  an  extension  of  a 
diphtheritic  inflammation  of  the  larynx  or  trachea. 


336         DISEASES  OF  THE  RESPIRATORY  ORGANS. 

THE  LUNGS, 

ATELECTASIS. 

Atelectasis  is  a  condition  in  which  the  lung  is  compressed 
or  collapsed,  so  that  there  is  an  absolute  absence  of  air  from 
the  air- vesicles. 

Congenitally  it  occurs,  especially  posteriorly  and  at  the 
base  of  the  lungs,  from  some  mechanical  obstruction  of  the 
air-passages,  as  the  presence  of  meconium ;  or  an  inability  to 
take  a  full  inspiration,  as  the  result  of  extreme  weakness. 
Under  these  circumstances  the  term  apneumatosis  is  some- 
times applied.  The  affected  areas  are  bluish,  and  so  solid 
that  if  a  portion  is  thrown  into  water  it  sinks. 

Later  in  life  a  large  pleuritic  effusion,  or  a  Avound  in  the 
chest-wall,  may  result  in  the  collapse  of  a  whole  lung.  A 
lobular  collapse  occurs  in  broncho-pneumonia,  and  is  supposed 
to  result  from  a  valve-like  obstruction  of  a  bronchiole  by  a 
plug  of  mucus,  which  cannot  be  dislodged  by  inspiration,  but 
permits  the  air  to  escape  from  the  lobules  supplied.  The 
tissue  is  dry  and  tough,  has  a  firm,  flesh-like  feel,  does  not 
crepitate,  and  sinks  if  placed  in  water.  If  the  condition  per- 
sists, there  is  finally  an  entire  and  permanent  obliteration  of 
the  air-vesicles  by  an  overgrowth  of  connective  tissue. 

EMPHYSEMA . 

Interstitial  emphysema  is  a  condition  analogous  to  emphysema 
of  subcutaneous  tissues ;  there  is  an  accumulation  of  air  in 
the  connective-tissue  septa  between  the  lobules  of  the  lung  as 
the  result  of  rupture  of  an  air-vesicle.  It  occurs  most  fre- 
quently in  the  course  of  whooping-cough  or  broncho-pneu- 
monia in  young  children  ;  and  from  excessive  straining-efforts 
in  parturition,  defecation,  coughing,  etc. 

By  vesicular  emphysema  we  understand  a  dilatation  of  the 
air-vesicles  which  occurs  as  the  result  of  a  weakened  condi- 
tion of  the  lung-tissue  from  inflammatory  or  degenerative 
processes,  lessening  its  ability  to  resist  increased  pressure 
within,  from  such  causes  as  chronic  cough,  blowing  of  wind- 
instruments,  etc.  The  lungs  are  considerably  larger  than 
normal  j  there  is  a  gritty  feeling  on  section,  and  the  dilatation 


PASSIVE  HYPER^EMIA.  337 

of  the  air-spaces  may  be  so  great  as  to  be  apparent  to  the 
naked  eye. 

Microscopically  the  air-vesicles  are  found  to  be  rounded  in- 
stead  of  polygonal,   and   are   increased   in   diameter.     The 

FIG.  147. 


Section  from  an  emphysematous  lung  (Ribbert).  The  pulmonary  alveoli  are  en- 
larged; their  walls  are  stretched  and  thinned;  atrophied  because  of  repeated 
excessive  air-pressure  within  the  alveoli.  In  more  extreme  cases  of  emphysema 
the  atrophy  of  the  alveolar  walls  may  lead  to  their  total  destruction  in  places, 
so  that  the  cavities  of  neighboring  alveoli  communicate.  (Compare  with  Fig. 
149.) 

alveolar  walls  are  thinned  (see  Fig.  147)  ;  and  the  bloodvessels, 
being  stretched  over  a  larger  surface,  are  narrowed,  the 
anaemia  of  the  lung-tissue  thus  produced  further  favoring  the 
atrophy  and  degenerative  changes  in  the  alveolar  septa.  As 
a  remote  consequence  of  the  increased  pulmonary  blood -pressure 
there  is  hypertrophy  of  the  right  heart. 

PASSIVE  HYPER^SMIA. 

Passive  hypersemia,  brovm  induration,  or  brown  oedema,  re- 
sults from  some  obstruction  to  the  outflow  of  blood  from  the 
lungs,  most  frequently  from  some  myocardial  degeneration,  or 
valvular  lesion,  especially  mitral;  though  it  may  occur  in 
connection  with  aortic  stenosis,  or  regurgitation. 

22-Hist. 


338         DISEASES  OF  THE  RESPIRATORY  ORGANS. 

The  lungs  are  heavy  and  somewhat  larger  than  normal. 
On  section  they  are  dark  red  in  color,  and  on  pressure  a 
brownish-red  serum  exudes,  frothy  from  admixture  of  air — 
oedema.  In  other  and  more  chronic  cases  the  lung-tissue  is 
dry  and  indurated. 

Microscopically,  in  cases  in  which  the  brown  induration  is 
marked,  there  is  considerable  increase  in  the  connective  tissue 
of  the  lung ;  the  pleura,  interlobular  septa,  and  alveolar  walls 
are  thickened  and  pigmented.  The  alveolar  walls  have  a 
beaded  appearance,  due  to  the  passive  engorgement  of  the 
capillary  bloodvessels.  Within  the  air-spaces  are  red  blood- 

FIG.  148. 


Brown  induration  of  lung,  d,  prominent  capillaries  in  alveolar  wall ;  a,  cells  con- 
taining pigment  in  lumen  of  alveolus;  6,  c,  alveolar  epithelium.  X  250 
(Schmaus). 

corpuscles,  numerous  leukocytes,  and  desquamated  epithelial 
cells — many  of  which  contain  pigment  derived  from  the 
altered  red  blood-corpuscles  which  they  have  englobed  and 
digested  (see  Fig.  148).  Later,  these  cells  having  been  taken 
into  the  lymphatic  system,  the  pigment  is  thus  distributed. 

(Edema  of  the  lungs  may  also  result  from  active  congestion, 
produced  by  inhalation  of  very  hot  or  cold  air,  irritating 
gases,  etc.  Microscopically  the  alveoli  are  found  to  contain  a 
few  leukocytes,  desquamated  epithelial  cells,  and  a  granular 
debris  representing  the  coagulated  serous  exudate. 


LOBAR  PNEUMONIA.  339 

HEMORRHAGIC   INFARCT. 

Infarctions  are  usually  multiple,  and  occur  in  the  centre  of 
the  lower  lobe,  or  near  the  root  of  the  lung ;  when  superficial 
they  form  a  slight  elevation  beneath  the  pleura.  They  are 
wedge-shaped,  firm,  brown  in  color,  and  are  separated  by  a 
distinct  line  of  demarcation  from  the  surrounding  lung-tissue. 

FIG.  149. 

r 


Hemorrhagic  infarct  of  the  lung  (Kaufmann).  The  section  contains  a  portion  of 
the  plugged  vessel  beyond  the  site  of  the  embolus.  It  and  the  pulmonary 
alveoli  are  filled  with  blood,  which,  in  the  latter,  has  passed  through  the  capil- 
lary walls,  rendered  pervious  by  malnutrition.  This  blood  may  be  derived 
from  the  pulmonary  vein  and  also  from  the  bronchial  artery,  which  communi- 
cates with  the  capillaries  of  the  alveolar  walls. 

Microscopically  the  air-spaces  are  found  to  be  crowded  with 
red  blood-corpuscles  (see  Fig.  149). 

Pneumonia  is  the  term  employed  to  designate  inflammation 
of  the  lung,  in  contradistinction  to  inflammation  of  the  bronchi 
or  pleura.  Histologically  and  clinically  there  are  several 
well-defined  varieties  of  pneumonia  : 

LOBAR  PNEUMONIA. 

Lofcar  pneumonia  is  an  acute,  infectious,  self-limited  disease, 
with  a  definite  clinical  course,  and  characterized  pathologic- 
ally by  an  extensive  inflammation  of  the  lung,  involving  an 
entire  lobe. 


340         DISEASES  OF  THE  RESPIRATORY  ORGANS. 

Etiology :  The  diplococcus  pneumonice  is  found  in  the  inflam- 
matory exudates  and  in  the  sputum ;  it  is  the  micro-organ- 
ism most  frequently  associated  with  the  disease,  though  the 
pneumococcus  of  Friedlander,  streptococcus,  staphylococcus, 
typhoid  bacillus,  and  bacillus  of  influenza  seem  to  be  capable 
of  producing  similar  lesions. 

The  lower  lobe  of  the  right  lung  is  most  frequently  affected. 

Division  of  process :  The  inflammatory  process  may  be  di- 
vided into  three  stages :  engorgement,  red  and  gray  hepati- 
zation. 

In  the  stage  of  engorgement,  or  congestion,  the  affected  area 
is  deep  red  in  color,  crepitates  less  and  is  somewhat  firmer 
than  normal,  but  is  not  solidified,  does  not  sink  if  placed  in 
water ;  the  overlying  pleura  is  dull  and  lustreless.  On  sec- 
tion a  bright  red,  frothy  fluid  exudes  on  pressure. 

Microscopically  the  capillary  bloodvessels  of  the  alveolar 
walls  are  greatly  distended  with  blood  and  encroach  some- 
what upon  the  air-spaces,  within  which  are  a  large  number  of 
red  blood-corpuscles,  and  a  few  leukocytes  and  desquamated 
epithelial  cells.  A  similar  exudate  is  seen  in  the  smaller 
bronchi. 

In  the  stage  of  red  hepatization  the  inflammatory  exudate 
which  has  poured  into  the  air-spaces  has  coagulated  and  com- 
pletely solidified  the  lung-tissue,  giving  it  a  liver-like  consis- 
tency. On  pressure  the  affected  area  does  not  crepitate,  is 
firm  to  the  touch,  yet  friable,  and  if  placed  in  water  sinks. 
It  is  swollen,  and  upon  the  external  surface  the  ribs  have  left 
an  imprint.  The  pleura  is  often  coated  with  a  fibrinous  exu- 
date. On  section  the  surface  is  bright  red,  smooth  and 
glistening  ;  later,  as  the  fibrinous  plugs  within  the  air  spaces 
contract,  the  surface,  especially  if  torn,  has  a  granular  appear- 
ance, and  with  a  little  care  the  projecting  alveolar  plugs  may 
be  lifted  or  scraped  from  the  air-spaces,  of  which  they  form  a 
perfect  mould. 

Microscopically  the  air-vesicles  are  completely  filled,  even 
distended,  with  the  inflammatory  exudate.  The  exuded  blood- 
serum  has  coagulated,  and  the  fine  fibrillse  of  fibrin  entangle 
within  their  meshes  a  large  number  of  red  blood-corpuscles 
and  migrated  leukocytes  and  a  few  epithelial  cells  derived 
from  the  swollen  and  proliferating  epithelium  of  the  alveolar 


LOB  AM  PNEUMONIA. 


341 


walls.  The  exudate  in  the  bronchioles  and  on  the  pleural 
surface  is  composed  of  similar  elements.  The  capillary  blood- 
vessels of  the  delicate  walls  of  the  air-spaces  are  much  less 

FJG.  150. 


Section  from  lung  in  the  second  or  exudative  stage  of  croupous  pneumonia,  a,  en- 
dothelial  wall  of  a  small  vein :  6,  blood  within  the  vein,  unusually  rich  in  leu- 
kocytes, which  have  collected  during  the  slowing  of  the  circulation.  The  line 
6  points  to  the  nucleus  of  a  leukocyte.  Part  of  the  blood  has  fallen  out  of  the 
section  during  its  preparation,  c,  leukocytes  beneath  the  endothelium  of  the 
vascular  wall;  d,  oedematous  fibrous  tissue  surrounding  the  vessel.  The  fibres 
of  the  tissue  have  been  separated  by  the  exuded  serum.  This  tissue  is  also 
moderately  infiltrated  with  leukocytes  that  may  have  passed  through  the  walls 
of  the  vein,  and  contains  a  few  red  blood-corpuscles,  e,  wall  separating  two 
pulmonary  alveoli.  This  is  also  somewhat  infiltrated  with  leukocytes.  /,  exu- 
date within  an  alveolus,  consisting  of  serum,  fibrin,  leukocytes,  and  red  blood- 
corpuscles  ;  it  also  contains  a  few  epithelial  cells  desquamated  from  the  alveolar 
wall,  g. 

prominent  than  in  the  first  stage,  but  are  surrounded  by 
migrated  leukocytes  and  proliferating  connective-tissue  cells, 
forerunners  of  the  hyperplasia  of  connective-tissue  which 
occurs  in  some  chronic  pneumonic  processes  (see  Figs.  150 
and  151). 

In  the  stage  of  gray  hepatization  the  lung- tissue  still  re- 
mains solid,  but  becomes  mottled  in  appearance,  and  finally 
a  uniform  gray  in  color. 

Microscopically  it  is  found  that  the  red  blood  corpuscles 
have  become  decolorized  or  have  disappeared,  and  the  fibrin 
filaments  are  broken  down  and  granular.  The  exudate  does 


342         DISEASES  OF  THE  RESPIRATORY  ORGANS. 

not  now  entirely  fill  the  air-spaces ;  it  is  composed  mainly 
of  leukocytes,  which  have  greatly  increased  in  number  and 
are  now  undergoing  a  fatty  degeneration  (see  Fig.  152). 

If  the   patient   survives,    the   inflammatory   process   may 
terminate  in  resolution,  abscess  formation  or  gangrene. 

FJG.  151.  . 


Croupous  pneumonia— red  hepatization.  Three  alveoli  filled  with  fibrinous  ex- 
udate.  In  the  latter  a  mesh-work  of  fibrin  (/),  desquamated  alveolar  epithelium 
(e),  leukocytes  (I),  and  red  blood-corpuscles,  a,  alveolar  septa  with  capillaries. 
X  250  (Schmaus). 

Resolution  is  the  most  frequent  termination,  and  is  brought 
about  by  a  fatty  degeneration  and  liquefaction  of  the  exudate, 
which  is  finally  absorbed  by  the  lymphatics,  or  expectorated. 

Abscess-formation  as  the  result  of  secondary  infection  with 
pyogenic  micro-organisms  is  a  rare  termination.  It  occurs 
most  frequently  in  the  upper  lobes. 

Gangrene  also  is  a  rare  termination.  It  is  especially  liable 
to  occur  in  the  drunkard,  and  in  cases  in  which  the  circulation 
is  exceedingly  weak. 

Associated  lesions :  Although  the  inflammatory  process  in 
the  lungs  is  the  characteristic  feature  of  lobar  pneumonia,  not 
infrequently  there  are  widespread  pathological  changes  due  to 
the  general  systemic  intoxication.  Circulatory  failure  due  to 


LOEULAR  PNEUMONIA. 


343 


degenerative  changes  in  the  myocardium  is  the  most  frequent 
cause  of  death. 

FIG.  152. 


Croupous  pneumonia — gray  hepatization — showing  the  large  accumulation  of  cellu- 
lar elements  within  one  of  the  pulmonary  alveoli,  which  in  some  parts  have 
undergone  such  extensive  fatty  degeneration  that  their  distinctive  outlines  are 
no  longer  visible.  X  200  (Green). 

LOBULAR  PNEUMONIA. 

In  lobular  or  bronchopneumonia  the  inflammatory  process 
does  not  involve  large  areas  of  lung-tissue,  though  the  coales- 
cence of  the  smaller  lobular  areas  of  consolidation,  which  are 
more  or  less  widely  distributed  throughout  both  lungs,  may 
simulate  a  lobar  pneumonia. 

Etiology :  Lobular  pneumonia  may  be  a  primary  affection  ; 
but  it  is  much  more  frequently  secondary,  occurring  in  the 
course  of  influenza,  wThooping-cough,  measles,  and  other  infec- 
tious diseases.  In  animals  it  can  be  experimentally  produced 
by  causing  them  to  inhale  steam  or  other  irritating  vapors; 
or  by  section  of  both  vagi — the  glottis  being  rendered  insen- 
sitive, saliva  and  portions  of  food  carrying  harmful  micro- 
organisms are  brought  to  the  finer  bronchi  by  inspiration. 


344        DISEASES  OF  THE  RESPIRATORY  ORGANS. 

Bacteria  play  an  important  part  in  the  production  of 
catarrhal  pneumonia,  though  no  one  organism  is  recognized 
as  the  specific  cause.  In  a  large  percentage  of  cases  FriinkePs 
pneumococcus  is  found. 

Lesions:  The  inflammatory  process  seems  always  to  begin 
in  the  terminal  bronchioles,  and  to  extend  by  contiguity  and 
continuity  to  surrounding  lung-tissue. 

Scattered  through  both  lungs  there  is  a  variable  number 
of  solid  patches,  some  of  which  are  due  to  collapse  of  the  air- 
vesicles,  while  some  are  the  result  of  inflammatory  exudation. 
The  collapsed  areas  vary  from  one -tenth  to  one-fifth  of  an 
inch  in  diameter,  and  are  depressed  below  the  surface  of  the 
lung-tissue.  The  pneumonic  patches  vary  from  the  size  of  a 
pea  to  that  of  a  hazelnut  or  walnut,  and  are  raised  above  the 
surface ;  the  overlying  pleura  may  be  somewhat  opaque  from 
inflammatory  exudation ;  the  surrounding  pulmonary  tissue 
is  often  more  or  less  emphysematous. 

As  a  whole  the  lungs  are  congested  but  crepitant ;  the  solid 
patches,  however,  are  airless  and  sink  in  water.  On  section 
the  areas  of  collapse  are  found  to  be  more  or  less  conical  in 
outline,  with  the  apex  directed  toward  the  bronchi  with  which 
they  are  connected.  The  pneumonic  patches  are  soft  and 
friable,  at  first  dark  red,  and  later  grayish-yellow  in  color ; 
they  are  not  separated  by  a  sharp  line  of  demarcation  from 
the  surrounding  tissue.  By  the  coalesence  of  such  patches 
nearly  a  whole  lobe  may  be  involved,  in  which  case  it  is  often 
difficult  to  distinguish  from  the  consolidation  of  a  lobar 
pneumonia.  The  cut  surface  of  such  an  area  is  smooth,  how- 
ever, not  granular ;  irregular  in  outline ;  and  there  are 
neighboring  smaller  areas  which  have  not  as  yet  become  fused 
to  the  larger  one. 

The  inflammatory  process  is  sometimes  divided  into  two 
stages,  red  and  gray  splenization.  corresponding  to  red  and 
gray  hepatization  of  the  lobar  variety. 

Microscopically ,  in  the  early  stage  of  red  splenization,  if  a 
single  lobule  is  examined,  we  note  in  the  centre  a  small 
bronchus  with  infiltrated,  thick  walls ;  its  lumen  may  be 
filled  with  leukocytes  and  desquamated  epithelial  cells.  The 
interlobular  connective  tissue  and  alveolar  walls  are  also 
infiltrated  and  thickened  by  proliferating  connective-tissue 


CHRONIC  INTERSTITIAL  PNEUMONIA.  345 

cells  and  migrated  leukocytes.  The  air-spaces  immediately 
surrounding  the  bronchus  are  filled  with  a  fibrillary  network 
of  fibrin,  a  variable  number  of  red  and  white  blood-corpus- 
cles, and  epithelial  cells.  A  little  further  from  the  bronchus 
the  air-spaces  contain  only  the  large,  flat,  rounded  or  oval  cells 
derived  from  the  proliferating  epithelium  which  lines  the 
alveolus. 

In  the  later  stage  of  gray  spleiiization  there  are  fatty  degene- 
ration and  liquefaction  of  the  alveolar  exudate,  part  of  which 
is  finally  expectorated  and  part  absorbed  by  the  lymphatics. 

Resolution  is  the  usual  termination.  With  the  absorption 
of  the  alveolar  exudate  the  round-celled  infiltration  of  the 
walls  disappears ;  the  whole  process  takes  much  longer,  how- 
ever, than  in  lobar  pneumonia. 

CHRONIC  INTERSTITIAL  PNEUMONIA. 

Chronic  interstitial  pneumonia,  or  fibrosis,  is  characterized  by 
an  excessive  formation  of  new  fibrous  tissue,  involving  the 
alveolar  walls  and  the  supporting  connective-tissue  frame- 
work of  the  lungs.  It  may  be  secondary  to  lobar  or  lobular 
pneumonia,  or  due  to  the  inhalation  of  solid  irritating  patches 
— pneumokoniosis. 

The  affected  lung  is  generally  smaller  than  normal,  and 
feels  firm,  fibrous,  and  elastic  ;  bronchiectatic  cavities  are  fre- 
quently met.  When  due  to  the  inhalation  of  particles  of  coal 
or  carbon — anthracosis — the  lungs  are  deeply  pigmented  ; 
similar  lesions  occur  in  artificers  in  iron  and  steel — siderosis — 
only  the  coloration  is  brown  instead  of  black  ;  silicosis  is  the 
term  applied  to  an  analogous  condition  in  quarry  men,  in 
which  the  lungs  have  a  marble-like  or  slate-like  appearance, 
produced  by  inhalation  of  the  dust-particles  of  dry  silicious 
stone. 

Microscopically  there  is  noted  thickening  of  the  pleura, 
the  interlobular  septa  continuous  with  its  deeper  layer,  the 
peribronchial  and  peri  vascular  tissue,  and  the  interalveolar 
septa.  The  air-vesicles  are  compressed,  their  walls  thickened 
and  fibrous  (Fig.  153).  Following  lobar  pneumonia,  cases 
have  been  described  in  which,  in  addition  to  the  thickening 
of  the  walls  of  the  air-spaces,  there  was  organization  of  the 


346 


DISEASES  OF  THE  RESPIRATORY  ORGANS. 


alveolar  exudate  in  places;  appearing  even  a  few  days  after 
the  onset  of  the  disease,  were  intra-alveolar  plugs  of  newly 


FIG.  153. 


<**'     ••• 


Interstitial  pneumonia  (from  a  case  of  unilateral  "  cirrhosis"  of  the  lung).  The 
bronchi  were  much  dilated,  and  there  was  a  complete  absence  of  any  caseous 
change.  The  drawing  shows  the  new  fibre-nucleated  growth  both  in  the  alveolar 
walls  and  in  the  interlobular  tissue,  also  the  pigmentation.  At  a  a  divided 
vessel  is  seen.  With  a  higher  power  a  delicate  reticulum  is  visible  between  the 
cell-elements.  X  100  (Green). 

formed  fibrous  tissue,  well  supplied  with  bloodvessels  com- 
municating with  those  of  the  alveolar  walls. 


GANGRENE. 

Gangrene  of  the  lungs  occurs  as  the  result  of  obstruction 
of  the  pulmonary  or  bronchial  arteries,  and  in  the  course  of 
typhoid  and  other  infectious  diseases.  It  may  follow  a  pneu- 
monia ;  result  from  a  wound  of  the  lungs  ;  or  be  due  to  press- 
ure, as  by  an  aneurism  or  by  some  foreign  body  in  a  bron- 
chus. It  may  also  result  from  the  extension  of  necrotic  proc- 
esses from  neighboring  structures.  There  are  two  varieties  : 
the  circumscribed  and  the  diffuse. 

In  the  circumscribed  variety  there  are  usually  one  or  more 
small  foci  in  each  lung,  blackish,  even  greenish  in  appearance. 
These  foci  have  a  most  offensive  odor,  are  soft  and  pultaceous, 
and  are  surrounded  by  congested  or  hepatized  lung-tissue. 

Diffuse  gangrenous  areas  may  result  from  the  coalescence 


TUBERCULOSIS  OF  THE  LUNGS.  347 

of  smaller  foci,  or  may  be  diffuse  from  the  first  and  involve 
even  an  entire  lung. 

The  sputum  is  usually  intensely  foetid. 

THE  INFECTIVE  GRANULOMATA. 
TUBERCULOSIS  OF  THE  LUNGS. 

The  pathological  changes  in  the  lungs  produced  by  the 
tubercle  bacillus  vary  somewhat  with  the  different  modes  of 
infection,  whether  through  the  respiratory  passages,  the  blood 
or  lymph  channels  ;  also  with  the  number  and  virulence  of  the 
bacilli,  and  more  especially  with  the  ability  of  the  patient  to 
withstand  their  invasion.  This  last  depends  not  only  on  the 
state  of  one's  general  health,  but  also  on  one's  inherited  ten- 
dencies toward  the  disease,  the  importance  of  which  cannot  be 
overestimated.  Just  what  is  transmitted  to  an  individual 
who  inherits  a  predisposition  to  tuberculosis  cannot  be  stated 
further  than  that  there  is  a  soil  markedly  favorable  to  the 
growth  of  the  germ. 

Besides  the  characteristic  lesion — the  histological  tubercle 
— which  is  distinctive  of  the  pathological  changes  produced 
by  the  tubercle  bacillus,  these  organisms  are  capable  of  excit- 
ing tissue-changes  quite  similar  to  those  of  ordinary  simple 
inflammation.  As  in  simple  inflammations,  the  more  intense 
the  irritant  the  more  prominent  the  phenomena  of  cellular  and 
serous  exudation,  while  in  inflammations  of  longer  duration 
and  less  intensity  the  characteristic  feature  is  the  tendency 
toward  organization  and  production  of  new  fibrous  tissue;  so 
some  tubercular  inflammations  are  characterized  by  exudations 
and  others  by  proliferative  changes. 

When  the  bacilli  gain  access  by,  and  are  distributed  through 
the  medium  of  the  bronchial  tubes  in  large  numbers,  the  lesions 
are  not  so  sharply  circumscribed  as  they  are  when  the  organ- 
isms are  deposited  from  the  bloodvessels  here  and  there  in  the 
pulmonary  tissue  in  small  numbers  •  nor  are  they  of  the  same 
productive  type,  but  are  characterized  by  more  extensive 
exudation  and  a  greater  tendency  to  coagulation-necrosis, 
caseation,  and  the  involvement  of  larger  areas. 

In  the  bronchogenic  tubercular  inflammations  of  the  lungs, 
in  some  instances  there  is  a  tendency  for  the  areas  of  pneu- 


348         DISEASES  OF  THE  RESPIRATORY  ORGANS. 

raonic  consolidation  to  conform  to  the  distribution  of  the 
smaller  bronchi — histologically  the  alveolar  exudate  resembling 
that  of  lobular  pneumonia  ;  in  others  there  is  a  diffuse  hepatiza- 
tion  of  one  or  more  entire  lobes,  the  exudate  consisting  of  fibrin, 
leukocytes,  and  epithelial  cells,  as  in  lobar  pneumonia. 

To  those  cases  in  which  there  is  extensive  pneumonic  con- 
solidation and  subsequent  caseation  and  destruction  of  lung- 
tissue  the  term  phthisis  pulmonalis  is  often  restricted.  Origi- 
nally the  term  was  employed  to  designate  a  wasting  of  the 
whole  body  associated  with  disease  of  the  lungs.  The 
pulmonary  lesions,  later  recognized  as  characteristic  of  such 
cases,  were  both  "  ulcerative  "  and  nodular ;  gradually,  how- 
ever, smaller  nodules — tubercles — were  noted,  and  finally 
regarded  as  the  starting-point  of  the  older  destructive  lesions. 
In  its  modern  acceptation  the  term  phthisis  has  come  to  be 
used  in  connection  with  the  wasting  or  destruction  of  the  lung- 
tissue  rather  than  with  the  general  wasting  and  emaciation  of 
the  whole  body;  so  wre  find  most  authors  describe  separately 
phthisis  pulmonalis  and  miliary  tuberculosis. 

In  these  bronchogenie  forms  of  pulmonary  tuberculosis  the 
factors  concerned  in  the  production  of  a  lobular  distribution 
and  catarrhal  exudation  at  one  time,  and  a  lobar  distribution 
and  fibrin  cms  exudate  at  another,  may  not  be  understood ;  the 
character  of  the  associated  secondary  infection  is,  however, 
quite  possibly  one  explanation.  The  histological  tubercles 
which  are  often  noted  in  connection  with  these  pulmonic  con- 
solidations, especially  at  their  borders,  might  be  assumed  to 
be  due  to  the  penetration  of  stray  individual  organisms  between 
the  epithelial  cells  to  the  perialveolar  and  peri  bronchial  con- 
nective tissues.  These  pneumonic  consolidations  most  fre- 
quently begin  in  the  apices  of  the  lungs,  probably  as  the  result 
of  some  impairment  in  the  nutrition  of  the  lung-tissue  at  this 
point,  by  reason  of  lessened  aeration  of  the  blood  due  to 
diminished  range  of  the  respiratory  movements  at  the  apices ; 
general  feebleness  and  cardiac  weakness  still  further  favoring 
the  same  results. 

It  has  been  stated  that  when  the  tubercle  bacilli  are 
deposited  in  small  numbers  in  the  pulmonary  tissue  from  the 
bloodvessels,  the  lesions  are  different  from  those  produced  by 
the  entrance  of  large  numbers  through  the  respiratory  pas- 


ACUTE  MILIARY  TUBERCULOSIS.  349 

sages.  It  might  be  assumed  that  where  each  organism  is 
deposited  from  the  blood  there  results  the  accumulation  of 
epithelioid  and  lymphoid  cells,  with  possibly  a  giant-cell  in 
their  centre,  which  constitutes  the  typically  histological 
tubercle  ;  and  that  the  "  system  "  of  such  histological  tubercles, 
of  which  even  the  smallest  gray  miliary  tubercle  visible  to  the 
naked  eye  is  formed,  results  from  the  presence  of  as  many 
organisms.  Secondarily  are  noted  the  exudations  into  the 
surrounding  air-spaces.  The  conditions  which  hold  in  the 
lungs  differ  from  those  in  other  organs  of  the  body  on  account 
of  the  accessibility  of  the  former  not  only  to  the  tubercle 
bacilli  in  larger  numbers,  which  is  regarded  as  an  explanation 
of  the  greater  prominence  of  inflammatory  exudations,  but 
also  to  streptococci  and  other  secondarily  infecting  organisms, 
which  play  a  most  important  part  in  pulmonary  tuberculosis. 

Acute  Miliary  Tuberculosis. 

Acute  miliary  tuberculosis  occurs  usually  as  part  of  a  gene- 
ral miliary  tuberculosis,  which  not  infrequently  results  from 
the  rupture  of  some  tubercular  focus — such  as  a  caseous 
lymph-gland — into  a  bloodvessel ;  or  follows  operations  upon 
tubercular  joints  or  bones.  Clinically  the  disease  has  always 
had  a  peculiar  interest  on  account  of  its  resemblance  to 
typhoid  fever  at  certain  stages. 

The  lungs  are  congested  and  studded  throughout  with  small 
grayish,  gelatinous-looking  nodules  about  the  size  of  millet 
seeds  or  small  shot;  at  first  they  may  be  so  small  and  trans- 
lucent as  to  be  scarcely  visible  to  the  naked  eye,  though 
finally  becoming  quite  large,  especially  in  the  lungs  of  chil- 
dren. They  may  be  widely  separated  or  so  closely  set  as  to 
solidify  the  whole  lung.  Some  may  be  yellowish  from  ad- 
vancing caseation.  Microscopically  it  is  noted  that  these 
nodules  are  situated  in  the  intorlobular  or  interalveolar  septa, 
and  are  composed  of  several  histological  tubercles  (Fig.  154). 
In  these  acute  processes  giant-cells  are  not  often  seen,  the 
centre  and  often  the  entire  tubercle  being  caseous.  The  sur- 
rounding air-spaces  may  be  more  or  less  completely  filled 
with  inflammatory  exudates,  and  the  interalveolar  septa  con- 
siderably thickened. 


350        DISEASES  OF  THE  RESPIRATORY  ORGANS. 

In  more  chronic  cases,  in  which  perhaps  the  bacilli  are  less 
virulent  or  are  admitted  more  slowly  to  the  lungs,  the  nodules 
are  larger  and  not  so  numerous ;  the  areas  of  caseous  degen- 
eration are  much  more  extensive. 

FIG.  154. 


Acute  miliary  tuberculosis  of  the  lungs,  a,  a1,  a2,  a3,  tubercles  with  central  caseation, 
in  part  in  parenchyma  on  alveolar  tubes  (b,  bl),  in  part  situated  on  bloodvessels. 
In  many  tubercles  giant-cells.  X  40  (Schmaus). 

Acute  Phthisis. 

As  has  already  been  pointed  out,  the  main  features  of 
phthisis  are  the  lobar  and  lobular  consolidations,  which  are 
wont  speedily  to  undergo  caseation.  The  size  of  these  pneu- 
monic areas  may  vary  greatly. 

In  the  earlier  stages  grayish  miliary  patches,  one-twelfth  to 
one-sixth  of  an  inch  in  diameter,  stand  out  prominently  be- 
neath the  pleura  or  upon  the  congested  cut  surface  of  the 
lungs,  in  greatest  number  at  the  apices.  Microscopically  the 
patches  are  found  to  have  each  a  caseous  centre,  which  is 
structureless  and  granular  in  appearance — the  outline  of  the 
air-spaces  may,  however,  be  faintly  discernible;  further  away 


ACUTE  PHTHISIS. 


351 


from  this  central  zone  the  alveoli  are  filled  with  catarrhal  or 
fibrinous  exudations  (Figs.  155  and  156).  Near  the  centre 
of  the  patch  may  be  noted  a  bronchiole,  its  lumen  filled  with 
desquamated  epithelial  cells  and  a  granular  debris.  The  walls 
of  the  air- vesicles  and  bronchioles  are  infiltrated  and  somewhat 
thickened. 

At  a  later  stage  these  areas  of  consolidation  reach  the  size 
of  a  hazelnut  or  walnut,  or  they  may  involve  an  entire  lobe  or 
even  the  whole  lung.  Although  such  a  diffuse  consolidation 

FIG.  155. 


A  small  soft  gray  tubercle  from  the  lung  in  a  case  of  acute  tuberculosis.  The  whole 
of  the  tubercle  is  shown  in  the  drawing,  and  is  largely  constituted  of  intra- 
alveolar  products.  X  100,  reduced  to  £  (Green). 

may  appear  quite  as  uniform  as  that  of  lobar  pneumonia,  mi- 
croscopically there  is  usually  evidence  of  an  original  lobular 
character  of  the  inflammatory  process. 

On  section  the  surface  of  the  affected  areas,  which  have 
become  yellowish  in  color  as  the  result  of  extensive  caseation, 
is  generally  smooth,  though  it  may  have  a  granular  appear- 
ance when  the  character  of  the  inflammatory  exudate  is  fibrin- 
ous. The  lungs  may  be  fairly  riddled  with  small,  irregular 


352         DISEASES  OF  THE  RESPIRATORY  ORGANS. 

cavities  with  cheesy  walls,  resulting  from  the  breaking  down 
and  evacuation  of  the  caseous  material.  The  pleura  is  gener- 
ally thickened,  especially  over  the  apices. 

Microscopically  it  is  noted  that  the  areas  of  consolidation 
are  formed  of  the  smaller  patches  just  described,  each  with  a 
caseous  centre  and  an  outer  zone  of  air-spaces  filled  by  inflam- 
matory exudations.  The  peribronchial  connective  tissue  and 
alveolar  septa  are  infiltrated  as  in  lobular  pneumonia,  and 
occasionally  typical  histological  tubercles  may  be  seen  here 
and  there,  especially  at  the  periphery  of  the  pneumonic  areas. 

FIG.  156. 


Section  of  lung  from  a  case  of  acute  phthisis,  showing  that  the  consolidation  con- 
sists almost  exclusively  of  products  accumulated  within  the  alveoli.  In  some 
parls  a  free  space  is  seen  between  the  alveolar  walls  and  their  contents;  this 
is  due  simply  to  the  shrinking  of  the  latter  caused  by  hardening  of  the  speci- 
men. X  50  (Green). 

Besides  the  cases  whicli  conform  to  a  lobular  type  of  pneu- 
monia, others  have  been  described  which  resembled  lobar 
pneumonia,  not  only  in  the  character  of  the  inflammatory 
exudate,  but  also  in  its  lobar  distribution.  In  some  instances 
of  acute  phthisis,  tubercles  may  be  entirely  absent,  or  at  least 
indistinguishable  in  consequence  of  the  extensive  caseous  de- 
generation;  though  they  can  generally  be  found,  if  not  in  the 
lungs,  on  the  pleura,  or  peritoneum,  or  elsewhere. 


CHRONIC  PHTHISIS. 


353 


Chronic  Phthisis. 

Chronic  phthisis  is  the  common  form  of  pulmonary  tuber- 
culosis. The  primary  lesions  are  generally  found  in  the  apices 
of  the  lungs.  In  the  great  majority  of  cases  the  inspired  air 
is  the  source  of  the  infection,  though  occasionally  without 
doubt  the  tubercle  bacilli  are  introduced  through  the  blood  or 

FIG.  157. 


K  'Mig-r   • 

mm       v 


Wall  of  a  tubercular  cavity,  c,  cavity  ;  k,  cheesy  wall ;  c',  c",  small  recent  cavi- 
ties ;  t,  tubercle.  To  the  left,  fibrous  tissue  in  which  are,  6,  bronchi ;  g,  vessels. 
X  100  (Schmaus). 

lymph  channels — the  further  extension  of  the  disease  result- 
ing from  rupture  of  a  caseous  focus  into  a  bronchus  and  aspira- 
tion of  the  infected  material  into  other  parts  of  the  lungs. 

The  lungs  are  firmly  adherent  to  the  chest-wall  ;  the  pleural 
cavities  may  be  thus  entirely  obliterated.     The  pleurae  are 

23— Hist. 


354         DISEASES  OF  THE  RESPIRATORY  ORGANS. 

greatly  thickened — even  as  much  as  a  quarter  of  an  inch  at  the 
apices — and  fibrous,  and  may  be  studded  with  gray  gelatinous 
nodules.  On  sections,  most  characteristic  lesion  is  noted  :  the 
cavity,  which  results  from  liquefaction  of  caseous  areas  (Fig. 
157).  They  are  most  frequent  in  the  upper  lobes,  and  vary  in 
size  from  that  of  a  hazelnut  to  that  of  a  small  orange,  or  even 
much  larger,  and  have  glistening,  firm  fibrous  walls.  Espe- 
cially numerous  in  the  upper  part  of  the  lungs  are  noted 
irregularly  rounded,  opaque,  grayish  or  yellowish  areas  of 
consolidation. 

The  histological  changes  are  similar  to  those  in  acute 
phthisis,  except  as  modified  by  the  longer  duration  of  the 
inflammatory  process.  In  the  centre  of  these  areas  the 
tubercles  cannot  be  distinguished  on  account  of  the  caseous 
degeneration  which  has  taken  place  ;  at  the  periphery,  however, 
they  may  be.  Here  and  there  are  nodules  which  are  found  to 
be  composed  of  several  histological  tubercles.  The  centre  of 
such  a  system  of  tubercles  is  generally  caseous,  though  it  may 
be  firm  and  fibrous.  These  tubercles  are  situated  in  the  inter- 
alveolar  and  interlobular  septa,  and  may  be  seen  in  various 
stages  of  development.  They  are  generally  surrounded  by 
patches  of  catarrhal  or  fibrinous  exudation. 

Fibroid  Phthisis. 

In  fibroid  phthisis,  which  is  the  most  chronic  form  of  the 
disease,  the  reparative  efforts  on  the  part  of  nature  predomi- 
nate over  the  destructive  effects  produced  by  the  tubercle 
bacilli.  An  area  of  caseation  is  often  found  to  be  surrounded 
by  a  capsule  of  more  or  less  fully  developed  fibrous  tissue,  and 
thus  its  further  extension  is  arrested.  There  is  always  an 
especially  marked  increase  in  the  amount  of  interalveolar  and 
interlobular  connective  tissue,  which  leads  to  extensive  indu- 
ration of  the  lung-tissue. 

Tuberculosis  is  often  engrafted  upon  simple  chronic  inter- 
stitial pneumonia. 

The  complications  of  phthisis  are  numerous  and  important. 
The  pleura  is  nearly  always  implicated.  In  acute  cases, 
over  pneumonic  areas,  it  is  usually  the  seat  of  a  seropurulent 
or  fibrinous  exudation,  as  in  lobar  pneumonia  ;  or  a  diffuse 


SYPHILIS  OF  THE  LUNGS.  355 

acute  inflammation  may  result  from  rupture  of  a  tubercular 
focus  into  the  pleural  cavity.  In  more  chronic  cases  there 
are  almost  constantly,  extensive  adhesions  between  the  parietal 
and  visceral  layers. 

Extension  of  the  tubercular  process  in  the  lung  itself  is 
caused  by  the  aspiration  of  material  from  caseous  foci  to 
other  parts.  Sputum  loaded  with  tubercle  bacilli  is  very 
apt  to  infect  the  upper  air-passages,  and,  if  swallowed,  the 
gastro-intestinal  tract.  A  general  miliary  tuberculosis  may 
result  from  secondary  infection  of  the  blood — through  tuber- 
cular infiltration  of  the  vessel- wall  or  rupture  of  a  caseous 
focus  into  its  lumen. 

Pneumothorax  is  due  to  perforation  of  the  pleura.  The 
pleura  is  very  liable  to  undergo  necrosis  at  a  given  point  as 
the  result  of  an  underlying  focus  of  caseation  in  which  are 
involved  the  bloodvessels  which  nourish  it.  If  this  occurs 
before  pleuritic  adhesions  have  been  formed,  perforation  occurs. 
In  this  manner  are  explained  many  cases  in  which  an  acute 
pleurisy  seems  to  precede  the  development  of  the  pulmonary 
affection. 

Fatal  hemorrhage  may  result  from  erosion  of  one  of  the 
branches  of  the  pulmonary  artery. 

Anaemia,  emaciation,  and  fever  are  constant  accompaniments 
of  phthisis. 

Widespread  amyloid  changes  in  the  viscera  are  present  in 
a  large  number  of  cases. 

SYPHILIS  OF  THE  LUNGS. 

Syphilitic  inflammation  of  the  lungs  in  adults  is  rare;  though 
gummata,  appearing  as  grayish  or  yellowish  rounded  nodules, 
are  sometimes  observed.  They  may  undergo  central  necrosis, 
and  thus  result  in  the  formation  of  cavities. 

In  congenital  syphilis  there  is  sometimes  a  consolidation  of 
extensive  areas  of  lung-tissue,  to  which  the  term  white  pneu- 
monia has  been  given,  on  account  of  the  pale  and  anaemic 
appearance  of  the  affected  areas.  Microscopically  there  is 
noted  a  great  increase  in  the  connective  tissue,  as  in  chronic 
interstitial  pneumonia,  and  a  catarrhal  exudate  within  the 
alveoli. 


356        DISEASES  OF  THE  RESPIRATORY  ORGANS. 

OTHER  GRANULOMATA  AND  TUMORS. 

Actinomycosis  is  a  rare  affection  of  the  lungs  which  clini- 
cally and  pathologically  may  closely  resemble  tuberculosis. 
There  are  nodules  of  lobular  pneumonia  varying  in  size  from 
that  of  a  pea  to  a  cherry,  which  later  become  confluent  and 
undergo  softening,  resulting  possibly  in  cavity-formation. 
Microscopically  the  fungus  is  readily  recognized  within  these 
areas  and  in  the  sputum. 

Glanders  also  rarely  affects  the  lungs,  producing  either  dif- 
fuse inflammation  with  abscess-formations  or  isolated  charac- 
teristic nodules  which  microscopically  are  found  to  consist  of 
masses  of  round  cells. 

In  leprosy  the  lungs  are  frequently  affected,  the  lesions 
resembling  very  closely  those  of  tuberculosis. 

Tumors :  Fibromata,  lipomata,  chondromata,  sarcomata,  and 
carcinomata  are  sometimes  observed  in  the  lungs.  Secondary 
sarcoma  is  quite  common,  and  occurs  much  more  frequently 
than  primary.  Secondary  carcinoma  is  not  so  common  as 
secondary  sarcoma. 

THE   PLEURA. 

Hsemothorax  is  a  term  indicating  blood  in  the  pleural  cavity. 
It  may  result  from  rupture  of  an  aneurism,  or  fracture  of  the 
ribs  or  other  injury  to  the  chest. 

Hydrothorax  signifies  a  non-inflammatory  accumulation  of 
serum  in  the  pleural  cavity.  It  is  usually  bilateral,  occurring 
in  the  course  of  a  general  dropsy  due  to  some  chronic  heart 
or  kidney  disease,  or  to  changes  in  the  composition  of  the 
blood.  A  slight  serous  effusion  is  not  infrequent  just  before 
death.  If  the  amount  of  the  effusion  is  considerable,  it  may 
greatly  interfere  with  respiration. 

Pneumothorax :  Air  alone  is  rarely  present  in  the  pleural 
cavity.  It  is  usually  associated  with  a  serous  or  purulent 
effusion — hydropnetimothorax  or  pyopneumothorax.  It  may 
result  from  traumatic  rupture  or  penetrating  wounds  of  the 
pleura  ;  90  per  cent,  of  all  cases,  however,  are  due  to  pulmon- 
ary tuberculosis. 


PLEURITIS.  357 

PLEURITIS. 

Pleuritis,  pleurisy  or  inflammation  of  the  pleura,  is  nearly 
always  secondary  to  an  adjacent  inflammatory  process,  as 
pericarditis,  pneumonia,  gangrene  or  tuberculosis  of  the  lungs. 
It  may  occur  in  the  course  of  some  general  disease,  as  pyaemia, 
septica3mia,  typhoid  fever,  influenza,  and  other  infectious  dis- 
eases, rheumatism,  gout,  and  Bright's  disease. 

Several  varieties  are  usually  described  according  to  the  char- 
acter of  the  inflammatory  exudate :  fibrinous,  serofibrinous, 
and  purulent. 

The  fibrinous  variety  is  generally  confined  to  circumscribed 
areas,  though  it  may  involve  the  entire  pleura  on  one  side. 
At  first  the  membrane  is  congested  and  its  normal  glistening 
appearance  is  lost,  due  to  the  cloudy  swelling  of  the  endo- 
thelial  cells,  the  exudations  and  other  phenomena  character- 
istic of  the  early  stage  of  inflammation.  The  serous  exudate, 
rich  in  fibrin,  coagulates  in  the  form  of  a  thin  white  pellicle 
on  the  surface,  varying  in  thickness  in  different  cases.  Where 
opposed  surfaces  have  become  agglutinated,  on  separation 
there  is  often  a  shaggy  appearance  somewhat  similar  to  that 
produced  by  pressing  together  the  buttered  surfaces  of  two 
pieces  of  bread — "  bread-and-butter"  pleurisy. 

Microscopically  may  be  noted  the  dilated  bloodvessels,  sur- 
rounding which  and  infiltrating  the  connective  tissue  are 
numberless  migrated  leukocytes.  The  thin  pellicle  on  the 
surface  of  the  pleura  consists  of  a  delicate  network  of  fibrin- 
filaments,  containing  in  its  meshes  migrated  leukocytes,  red 
blood-corpuscles,  and  possibly  a  few  desquamated  endothelial 
cells,  resembling  thus  very  closely  the  alveolar  exudate  in  the 
stage  of  red  hepatization  of  pneumonia.  At  this  stage  opposed 
pleural  surfaces,  which  are  found  adherent,  can  readily  be  sep- 
arated. Later,  however,  on  this  temporary  scaffolding  of 
fibrin  a  new  connective  tissue  is  built,  through  the  agency  of 
the  leukocytes  and  proliferating  endothelial  cells,  which 
results  finally  in  firm  fibrous  adhesions. 

The  serofibrinous  variety  may  be  simply  a  more  advanced 
stage  of  the  inflammatory  process.  The  quantity  of  the 
serous  exudate  which  accumulates  in  the  pleural  cavity  varies 
ereatly — it  may  exceed  four  litres. 


358         DISEASES  OF  THE  RESPIRATORY  ORGANS. 

Microscopically  the  serous  exudate  is  found  to  contain  a  few 
white  and  red  corpuscles  and  desquamated  endothelial  cells. 
In  chemical  composition  and  physical  appearances  it  resembles 
blood-serum.  When  the  effusion  is  excessive  the  lung  is 
compressed  against  the  vertebral  column,  airless  and  almost 
bloodless. 

Empyema:  A  purulent  effusion  into  the  pleural  cavity 
results  either  primarily  from  the  presence  of  some  pus-pro- 
ducing micro-organism,  or  from  secondary  infection  of  a  simple 
serous  effusion.  The  micro-organisms  most  frequently  found 
are  the  pneumococcus,  streptococcus,  staphylococcusand  tuber- 
cle bacillus;  occasionally  the  bacillus  coli,  typhoid  and  others. 
The  pleura  is  greatly  thickened,  and  on  its  surface  are  more 
or  less  abundant  granulations.  A  localized  necrosis  may 
result  in  perforation  of  the  pleura  and  discharge  of  the  effu- 
sion externally  through  the  thoracic  wall,  into  the  lungs,  or 
through  the  diaphragm  into  the  peritoneal  cavity. 


CHAPTER    VI. 
DISEASES  OF  THE  GASTROINTESTINAL  TRACT. 

THE  MOUTH. 

To  inflammation  of  the  mucous  membrane  of  the  mouth 
the  term  stomatitis  is  applied. 

Catarrhal  stomatitis  is  a  simple  inflammation  unattended  by 
ulceration.  It  occurs  most  frequently  in  children,  and  results 
from  a  great  variety  of  causes,  such  as  food  which  is  too  hot 
or  too  cold,  lack  of  cleanliness,  etc.  The  mucous  membrane 
is  congested  and  swollen,  and  either  unduly  dry  or  there  is 
an  increased  production  of  its  mucous  secretion. 

Croupous  or  pseudomembranous  stomatitis  is  nearly  always 
due  to  the  extension  of  a  similar  inflammation  in  thepliaryrix, 
produced  by  the  bacillus  of  diphtheria. 

Ulcerous  stomatitis  occurs  most  frequently  between  the  ages 
of  four  and  ten  years;  though  it  may  occur  in  adults  in  local- 
ized epidemics,  in  camps  and  garrisons.  Certain  drugs,  espe- 
cially mercury,  are  capable  of  producing  similar  lesions.  The 
inflammatory  process  begins  on  the  border  of  the  gums 
and  extends  to  the  lips,  cheeks,  and  edges  of  the  tongue.  The 
ulcers  which  form  on  the  lips  and  cheeks  may  become  quite 
large.  Suppuration  and  destruction  of  tissue  around  the 
teeth  may  be  so  great  that  they  finally  become  loosened  and 
fall  out. 

Aphthous  stomatitis  also  occurs  most  frequently  in  children. 
Bad  hygiene,  and  debility  resulting  from  prolonged  illness,  are 
predisposing  causes.  It  is  characterized  by  the  presence  of 
small  yellowish-white  patches  (aphthce),  lying  on  an  inflamed 
base,  and  varying  in  size  from  that  of  a  hemp-seed  to  that  of 
a  split  pea.  The  lesion  first  appears  as  a  small  red  papule  with 
a  whitish  centre.  By  the  end  of  twenty-four  hours  this  white 
central  area  of  degenerated  epithelial  cells  involves  the  whole 
patch.  The  inflammatory  process  seldom  leads  to  liberation. 

359 


360    DISEASES  OF  THE  GASTRO-INTESTINAL   TRACT. 

Gangrenous  stomatitis,  noma,  or  canerum  oris,  is  a  rare  affec- 
tion, characterized  by  a  spreading  gangrene  of  the  cheek,  gen- 
erally involving  one  side  only ;  it  is  nearly  always  fatal.  It 
occurs  most  frequently  in  weakly,  ill-nourished  children, 
especially  after  some  exhausting  acute  infectious  disease.  The 
earliest  lesion  usually  noted  is  a  sloughing  ulcer  on  the  inside 
of  the  cheek,  near  the  corner  of  the  mouth.  The  mucous 
membrane  becomes  black  and  gangrenous,  and  soon  the  proc- 
ess involves  the  entire  thickness  of  the  cheek  and  extends  in 
all  directions. 

Thrush,  or  muguet,  is  a  mycotic  stomatitis,  due  to  a  fungus, 
the  oi'dium  albicans,  occurring  especially  in  infants.  It  is 
characterized  by  the  presence  of  white  patches,  resembling 
curdled  milk,  upon  the  mucous  membrane.  There  is  a  ten- 
dency for  these  patches  to  extend  and  involve  the  pharynx, 
and  even  the  gastro-intestinal  tract.  If  a  white  patch  is  re- 
moved, the  underlying  mucous  membrane  is  red,  eroded,  and 
may  bleed.  Microscopically  the  white  deposit  is  found  to  be 
composed  of  the  delicate  filaments  of  the  parasite  and  degen- 
erated epithelial  cells. 

All  the  infectious  granulomata  may  affect  the  mucous  mem- 
brane of  the  mouth. 

Tuberculosis  is  not  often  noted.  It  may  be  primary  or  sec- 
ondary. The  nodular  masses  undergo  caseation,  often  result- 
ing in  the  formation  of  ulcers  closely  resembling  those  of 
tertiary  syphilis. 

Syphilis  affects  the  mouth  either  in  the  form  of  mucous 
patches  in  the  secondary  stage ;  or  gummata  varying  in  size 
from  that  of  a  pea  to  that  of  a  hazelnut,  in  the  tertiary.  The 
gummata  may  break  down  and  leave  deep  ragged  ulcers  in 
their  site. 

Tumors :  Flat-celled  carcinomata,  epitheliomata,  are  of  quite 
frequent  occurrence.  They  appear  first  as  a  small  nodule,  or 
circumscribed  infiltration,  which  soon  tends  to  ulcerate  and 
spread  rapidly. 

Sarcomata  usually  affect  the  gums,  sarcomatous  epulis. 


DIPHTHERIA.  361 

THE  PHARYNX. 

Simple  catarrhal  inflammation  of  the  pharynx,  or  simple  an- 
gina, is  due  to  exposure  to  cold,  or  occurs  in  the  course  of 
acute  infectious  fevers.  A  more  chronic  inflammation  may 
result  from  the  excessive  use  of  the  voice,  or  be  secondary  to 
some  disease  of  the  nasal  cavities.  The  mucous  membrane  is 
red  and  swollen.  In  some  cases  vesicles  form,  which  burst 
and  leave  behind  small  superficial  erosions.  Not  infrequently 
there  are  granulation-like  projections  above  the  surface  of  the 
mucous  membrane,  due  to  hypertrophy,  or  distention  of  the 
mucous  glands,  or  to  hyperpfasia  of  the  lymphatic  follicles. 

At  first  the  mucous  membrane  is  thickened,  but  later  it 
often  becomes  atrophic. 

Pseudomembranous  pharyngitis  is  in  most  instances  produced 
by  the  Klebs-Loffler  bacillus  diphtherise.  Lesions  in  every 
other  way  similar  are  sometimes  produced  by  other  micro- 
organisms, notably  the  streptococcus  pyogenes.  Such  "  diph- 
theritic" pseudomembranes  are  especially  frequent  in  scar- 
latina and  other  acute  infectious  diseases,  and  may  also  follow 
the  application  of  various  irritants  to  the  mucous  membrane. 

Diphtheria  is  an  acute  infectious  disease  characterized  by  a 
severe  toxaemia,  giving  rise  to  an  irregular  fever,  great  pros- 
tration, often  followed  by  cardiac  and  other  localized  or  gene- 
ral paralyses ;  and  locally  by  the  formation  of  a  pseudomem- 
brane  at  the  point  of  lodgment  of  the  diphtheria  bacilli,  either 
on  an  abraded  surface  or  a  mucous  membrane,  generally  that 
of  the  pharynx  and  upper  air-passages. 

The  pseudomembrane  is  grayish-white,  later  yellowish- 
white  in  color.  Small  patches  appear  on  the  posterior  pharyn- 
geal  wall,  the  tonsils,  soft  palate,  or  nares,  which  tend  rapidly 
to  extend  and  coalesce,  and  thus  may  cover  the  whole  pharynx  ; 
less  frequently  on  the  buccal  walls,  the  oesophagus,  stomach, 
vagina,  uterus,  and  on  surface  abrasions.  The  pseudomem- 
brane is  more  or  less  adherent,  and  if  removed  a  raw7  bleeding 
surface  may  be  left  behind.  The  formation  of  this  membrane 
is  the  result  of  the  severe  inflammatory  process  set  up  by  the 
diphtheria  bacilli.  The  serous  exudate  coagulates  and  entangles 
the  other  inflammatory  products.  Microscopically  it  is  found 


362    DISEASES  OF  THE  G  ASTRO-INTESTINAL   TRACT. 

to  be  composed  of  a  network  of  fine  fibrillse,  in  the  meshes  of 
which  are  red  blood-corpuscles,  migrated  leukocytes,  des- 
quamated epithelial  cells,  and  masses  of  micro-organisms.  The 
underlying  mucous  membrane  is  congested  and  infiltrated  with 
leukocytes;  its  epithelial  cells  are  undergoing  granular  de- 
generation or  coagulation-necrosis  (Fig.  158). 

FIG.  158 


Edge  of  a  diphtheritic  membrane.  Section  from  the  human  uvula  (Ziegler).  a, 
normal  stratified  epithelium  ;  b,  subepithelial  fibrous  tissue  of  the  mucous  mem- 
brane ;  c,  epithelium  that  has  undergone  coagulation-necrosis.  Only  remnants 
of  cells  remain  in  the  coarse  fibrinous  meshwork.  d,  oedematous  subepithelial 
fibrous  tissue  containing  fibrin  and  leukocytes ;  e,  bloodvessels  ;  /,  hemorrhage  ; 
g,  g,  groups  of  the  bacteria  causing  the  necrosis. 

The  associated  lesions  are  the  result  of  the  absorption  of 
toxins — the  bacilli  themselves  do  not  gain  entrance  to  the 
circulation.  The  neighboring  lymphatic  glands  are  usually 
greatly  swollen  ;  «the  kidneys  are  nearly  always  aifected,  as 
shown  clinically  by  the  albuminuria  which  is  present  in  the 
majority  of  cases — the  renal  epithelium  becomes  cloudy  and 
swollen,  and  minute  hemorrhages  are  sometimes  seen.  Not 
infrequently  there  are  necrotic  foci  in  the  liver,  and  in  nearly 
all  cases  some  myocardial  degeneration.  The  diphtheritic 
paralyses  are  due  to  degenerative  changes  in  the  nerve-centres 
and  peripheral  nerves. 


TONSILLITIS. 


363 


In  tonsillitis  the  inflammation  rnay  be  superficial  and  in- 
volve only  the  mucous  membrane  of  the  tonsil  as  part  of  a 
general  pharyngitis.  In  other  cases — lacunar  or  follicular 
tonsillitis — it  involves,  in  addition,  the  mucous  membrane 
lining  the  crypts,  which  become  distended  with  inflammatory 
products  and  project  above  the  surface  as  small  yellow  spots. 
The  exudations  at  the  mouth  of  adjacent  lacuna?  may  coalesce, 


FIG.  159. 


FIG.  160. 


Cicatricial  stricture  of  oesophagus  (War- 
ren Museum). 


A  very  tisht  stricture  of  the  oesophagus 
of  many  years'  duration,  apparently 
the  result  of  chronic  inflammatory 
action;  small  abscess  on  the  left 
(Warren  Museum). 


and  the  resulting  yellow  patch  somewhat  resembles  diphther- 
itic membrane.  Ulceration  of  the  walls  of  the  crypts  may  pro- 
duce quite  extensive  destruction  of  tonsillar  tissue.  In  other 
cases  the  inflammatory  process  ends  in  the  formation  of  an 


364    DISEASES  OF  THE  GASTEO-IXTESTINAL   TRACT. 

abscess — phlegmonous  tonsillitis  or  quinsy — the  tonsil  becom- 
ing so  large  as  to  project  beyond  the  median  line.  The  uvula 
and  epiglottis  are  often  cedematous,  and  the  submaxillary  and 
cervical  lymphatic  glands  enlarged. 


FIG.  161. 


FIG.  162 


A 


Traction  diverticulum  which 
was  adherent  to  a  cheesy 
bronchial  gland.  The  cut 
shows  the  external  oesoph- 
ageal  wall  with  the  diver- 
ticulum artificially  distend- 
ed (Warren  Museum). 


Congenital  malformation 
of  the  oesophagus.  Up- 
per portion  ends  in  a 
cul-de-sac ;  the  lower 
portion  opens  into  the 
trachea  (Harvard  Med. 
School,  Warren  Muse- 
um). 


Chronic  hypertrophy  may  follow  repeated  attacks  of  acute 
tonsillitis ;  usually,  however,  it  is  associated  with  hyper- 
trophy of  the  lymphoid  tissue  of  the  naso-pharynx — "  aden- 
oids." Microscopically  there  is  noted  an  increase  in  the  con- 
nective-tissue stroma  and  of  the  lymphoid  elements. 


THE  (ESOPHAGUS. 


365 


THE  SALIVARY  GLANDS. 

Inflammation  of  the  salivary  glands  may  occur  in  the  course 
of  various  acute  infectious  diseases,  as  septicaemia,  typhoid, 
etc. ;   or  result  from   a  special 
infection,  when  it  is  known  as  FIG.  163. 

mumps — the  parotid  gland  being 
most  frequently  affected. 

Mumps  rarely  terminates  in 
the  formation  of  an  abscess  in 
the  affected  gland,  while  this  is 
the  characteristic  tendency  in 
the  secondary  infections,  or 
metastatic  mumps. 

THE  (ESOPHAGUS. 

Inflammation  of  the  oesophagus 
may  be  due  to  ingestion  of  acids 
or  alkalies,  food  or  drink  too 
hot  or  too  cold,  the  lodgment 
of  foreign  bodies,  etc.  The  in- 
flammatory process  may  end  in 
ulceration  and  cicatricial  stenosis 
(Figs.  159  and  160). 

Cylindrical  dilatation  of  the 
oesophagus  results  from  long- 
continued  stenosis.  Sacculated 
dilatations  result  either  from, 
pressure  from  within  or  traction 
from  without,  as  by  contracting 
adhesions  (Figs.  161  and  162). 

Squamous-celled  carcinoma  is 
the  most  frequent  affection  of 
the  oesophagus  (Fig.  163).  It  generally  occurs  in  the  lower 
third,  though  it  may  be  found  in  any  part,  and  gradually 
produces  a  complete  stenosis. 


Cancer  of  oesophagus  (Warden    Mu- 
seum). 


366    DISEASES  OF  THE  G ASTRO-INTESTINAL   TRACT. 

THE  STOMACH. 

ALTERATIONS  IN  POSITION  AND  SIZE. 

Gastroptosis,  or  total  descent  of  the  stomach,  is  the  most  fre- 
quent displacement.  It  may  be  associated  with  similar  dis- 
placements of  the  other  abdominal  organs — enteroptosis,  or 
Glenard's  disease. 

Gastrectasia,  or  dilatation  of  the  stomach,  may  result  from 
pyloric  obstruction  produced  by  the  cicatrix  of  a  healing 
ulcer,  carcinoma,  pressure  of  a  tumor,  etc. ;  or  may  occur  in 
consequence  of  simple  atony  of  the  muscular  walls  brought 
about  by  overfeeding,  inflammatory  or  degenerative  changes. 
The  resulting  stagnation  of  the  stomach-contents  leads  to  ab- 
normal fermentations  and  a  train  of  symptoms  due  to  auto- 
intoxication. When  due  to  pyloric  obstruction  the  dilatation 
may  be  enormous.  At  first  there  may  be  compensatory  hyper- 
trophy of  the  muscle-walls  of  the  stomach  ;  but  later  they 
become  thin  and  atrophied,  and  the  mucous  membrane  non- 
absorptive. 

SIMPLE  ACUTE  GASTRITIS. 

Simple  acute  gastritis  is  an  exceedingly  common  condition. 
In  most  cases  it  results  from  dietetic  errors — excessive  in- 
dulgence, ingestion  of  food  which  has  undergone  partial  de- 
composition, or  is  too  hot  or  too  cold.  It  may  also  be  pro- 
duced by  various  chemical  irritants,  as  arsenic,  the  iodides  and 
salicylates,  even  in  therapeutic  doses.  The  mucous  membrane 
is  found  to  be  congested,  swollen,  covered  with  a  film  of 
glairy  mucus,  especially  in  the  pyloric  region,  and  punctated 
here  and  there  by  small  hemorrhagic  patches.  The  gastric 
secretion  is  reduced  in  quantity  and  quality,  a  fact  first  ob- 
served by  Beaumont,  through  a  gastric  fistula,  in  the  case  of 
the  Canadian,  Alexis  St.  Martin.  The  clinical  opportunities 
for  noting  the  marked  change  in  the  quality  of  the  gastric 
juice — the  hypochlorhydria,  etc. — are  numerous,  through  the 
use  of  the  stomach-tube. 

Microscopically  both  the  parietal  and  the  central  cells  of  the 
gastric  tubules  are  swollen  and  granular  ;  the  bloodvessels  of 
the  interglandular  connective  tissue  are  distended  and  sur- 


ACUTE  TOXIC  GASTRITIS.  367 

rounded  by  migrated  leukocytes.  At  a  later  stage  the  leuko- 
cytic  migration  becomes  more,  marked,  either  as  a  diffuse 
round-celled  infiltration  of  the  mucosa,  and  often  also  of  the 
submucosa,  or  confined  to  more  or  less  sharply  circumscribed 
patches.  The  lymph-follicles  are  often  hyperplastic. 

PURULENT  GASTRITIS. 

Purulent  or  phlegmonous  gastritis  is  a  rare  and  almost  in- 
variably fatal  affection.  It  occurs  in  the  course  of  puerperal 
fever,  pyaemia,  smallpox  and  similar  infections ;  or  it  may  be 
a  primary  condition.  The  inflammatory  process  is  either  cir- 
cumscribed or  diffuse.  In  the  former  case  there  is  generally 
but  one  abscess — most  frequently  situated  near  the  pylorus, 
and  varying  in  size  from  that  of  a  hazelnut  to  that  of  a  goose 
egg.  In  the  latter  case  there  is  a  diffuse  purulent  infiltration 
most  marked  toward  the  pylorus,  involving  first  the  sub- 
mucosa ;  later  the  mucosa  becomes  riddled  with  perforations, 
through  which  pus  wells  up.  The  muscle  and  serous  coats 
may  be  involved,  and  the  serous  surface  covered  with  a  puru- 
lent exudation. 

ACUTE  TOXIC  GASTRITIS. 

Acute  toxic  gastritis,  or  gastritis  venenata,  results  from  the 
ingestion  of  such  poisons  as  alcohol,  arsenic,  phosphorus, 
bichloride  of  mercury,  organic  and  inorganic  acids,  and 
caustic  alkalies. 

The  lesions  produced  vary  with  the  kind  and  quantity  of 
the  poison  taken  and  the  length  of  time  elapsing  before  death  ; 
they  are  associated  with  similar  changes  in  the  esophagus, 
and,  below  the  stomach,  in  the  small  intestine,  even  to  the 
ileocrecal  valve. 

The  inflammatory  process  excited  by  dilute  adds  and  alka- 
lies may  resemble  that  in  simple  acute  gastritis.  When  con- 
centrated  they  produce  local  death  of  the  tissues ;  and  if  the 
patient  survives,  most  serious  deformities  of  the  stomach 
may  result.  The  slough  involves  the  mucosa  and  often  also 
the  other  coats  of  the  stomach,  frequently  producing  a  perfo- 
ration. Adjacent  organs,  especially  the  liver  and  spleen,  are 
often  corroded  and  discolored  in  a  like  manner. 


368    DISEASES  OF  THE  GASTRO-INTESTINAL   TRACT. 

The  sloughs  produced  by  sulphuric  and  hydrochloric  acids 
are  dry  and  brittle,  and  ashy-gray  in  color,  or  black  and 
charred  in  extreme  cases  ;  those  of  nitric  acid  are  yellow.  The 
surrounding  tissue  is  the  seat  of  an  intense  hemorrhagic  in- 
flammation. The  sloughs  produced  by  the  caustic  alkalies 
are  not  brittle  but  soft,  and  have  somewhat  the  appearance  of 
a  soft  membrane.  Phosphorus,  arsenic,  and  antimony  in  large 
doses  produce  more  especially  a  fatty  and  mucoid  degeneration 
of  the  epithelial  cells  of  the  gastric  tubules,  resulting  in  an 
opaque,  yellowish-white  appearance  of  the  mucous  membrane. 

CHRONIC  GASTRITIS. 

The  systematic  clinical  use  of  the  stomach-tube  for  the  pur- 
pose of  obtaining  the  gastric  secretions  for  study,  within  recent 
years,  has  thrown  much  light  upon  the  pathological  physiology 
of  digestion.  And  the  microscopical  examination  of  pieces  of 
the  gastric  mucosa  found  in  the  washings  from  the  stomach 
has  added  greatly  to  our  knowledge  of  the  anatomical  lesions 
associated  with  the  well-defined  fundamental  types  of  chronic 
gastritis  recognized  clinically. 

The  character  of  the  exciting  cause  seems  to  bear  no  relation 
to  the  resulting  lesion.  Evidences  of  chronic  gastritis  are 
found  so  frequently  at  autopsy  that  a  terminal  gastritis  must 
be  looked  upon  as  an  almost  constant  accompaniment  of  the 
final  stages  of  all  chronic  diseases. 

More  or  less  pronounced  inflammatory  changes  are  asso- 
ciated with  organic  lesions  of  the  stomach,  as  ulcer  and  cancer. 
They  are  secondary  also  to  dilatation  and  atony  of  the  muscle- 
walls,  and  the  irritation  produced  by  the  resulting  stagnation 
of  the  stomach-contents  and  abnormal  fermentations  which 
take  place.  In  fact,  the  possible  causes  of  gastritis  are  so 
numerous  that  it  is  surprising  a  normal  stomach  should  be 
found  after  middle  life. 

The  most  frequent  causes  of  chronic  gastritis  as  an  inde- 
pendent and  primary  affection  of  the  stomach  are  dietetic — 
not  only  improper  food,  but  improper  methods  of  eating  it; 
bolting  the  food,  with  insufficient  mastication,  and  large 
draughts  of  liquid  which  are  often  unduly  hot  or  cold  ;  the 
excessive  use  of  condiments,  etc. 


GASTRITIS  GLANDULARIS  PROLIFERA.  369 

Gastritis  Mucipara. 

As  in  acute  gastritis,  the  changes  are  most  marked  in  the 
region  of  the  pylorus.  In  early  stages  of  the  inflammatory 
process  there  is  a  diffuse  redness  of  the  mucous  membrane, 
which  later  becomes  a  mottled  pale  gray.  The  mucosa  is 
swollen  and  covered  by  a  tenacious  layer  of  tough  mucus. 
Here  and  there  are  small  cysts,  produced  by  occlusion  of  the 
gastric  tubules.  Occasionally  it  is  studded  with  papillary 
projections  about  the  size  of  a  pea.  As  in  other  chronic  in- 
flammations, there  may  be  a  marked  increase  in  the  connec- 
tive-tissue stroma,  wrhich  results  finally  in  atrophy  of  the  gland- 
ular tissue. 

It  is  only  on  microscopic  examination,  however,  that  the 
distinctive  features  of  this  variety  of  chronic  gastritis  can  be 
noted.  The  number  of  gastric  tubules  in  a  given  field  is 
much  less  than  normal.  Most  characteristic  is  the  mucoid 
degeneration  of  the  chief  and  border  cells  of  the  tubules, 
extending  to  the  fundus  of  the  gland.  In  addition  to  these 
parenchymatous  changes,  there  is  a  more  or  less  pronounced 
cellular  infiltration  of  the  interglandular  connective  tissue. 
As  would  naturally  be  expected,  the  gastric  secretions  are 
greatly  reduced  in  quantity  and  quality,  and  in  late  stages 
even  entirely  wanting. 

Gastritis  Glandularis  Prolifera. 

This  variety  of  chronic  gastritis  stands  in  marked  contrast 
to  the  one  just  described.  The  distinctive  feature  here  is  the 
proliferative  activity  of  the  chief  and  parietal  cells  lining  the 
gastric  tubules,  the  parietal  or  acid-producing  cells  especially 
being  greatly  increased  in  size  and  number  and  lying  in  close 
juxtaposition.  These  oxyntic  or  parietal  cells  may  also  be 
found  in  the  tubules  of  the  pyloric  region,  where  they  are  not 
normally  present.  In  some  cases  there  seems  to  be  a  pro- 
liferation of  the  glandular  tubules,  the  entire  gland  becoming 
elongated  and  tortuous.  There  may  be  associated  with  these 
parenchymatous  changes  more  or  less  cellular  infiltration  of 
the  interglandular  connective  tissue. 

The  cylindrical   surface-epithelium  is  often  desquamated 

24— Hist. 


370    DISEASES  OF  THE  G ASTRO-INTESTINAL   TRACT. 

over  quite  extensive  areas,  and  ulcer  is  not  an  infrequent  com- 
plication. 

As  might  be  expected,  the  secretory  activity  of  the  gastric 
tubules  is  greatly  increased.  Not  only  is  the  quantity  of  the 
gastric  juice  augmented,  but  it  is  much  richer  in  pepsin  and 
hydrochloric  acid. 

Gastritis  Glandularis  Atrophica. 

Gastritis  glandularis  atrophica  may  occur  as  a  terminal 
stage  of  other  varieties  of  chronic  gastritis,  as  a  senile  change, 
or  complicating  various  chronic  diseases,  and  rarely  as  a 
primary  aifection.  It  is  characterized  by  a  degeneration  of 
both  the  cylindrical  cells  of  the  surface  of  the  mucous  mem- 
brane and  vestibular  alveoli,  and  the  cells  lining  the  gastric 
tubules.  The  former  undergo  a  mucoid,  and  the  latter  a 
granular  and  fatty  degeneration.  In  the  tubules  it  becomes 
impossible,  by  reason  of  their  loss  of  staining  properties  and 
indistinctness  of  outline,  to  distinguish  between  the  chief  and 
parietal  cells. 

Macroscopically  the  mucous  membrane  presents  a  smooth, 
thin,  white  surface.  In  addition  to  the  glandular  elements, 
the  submucosa  and  muscular  coats  may  be  involved  by  the 
atrophic  changes,  a  thin  layer  of  fibrous  tissue  taking  the 
place  of  the  latter.  In  other  cases  a  similar  destruction  of 
glandular  tissue  is  the  result  of  a  proliferation  of  the  inter- 
glandular  connective  tissue.  Instead  of  a  thinning  of  the 
stomach-wall,  it  may  be  greatly  thickened  by  an  overgrowth 
of  connective  tissue  beneath  the  mucosa — often  resulting  in 
great  reduction  of  the  size  of  the  organ,  even  to  a  capacity 
of  a  few  ounces. 

The  natural  result  of  these  lesions  is  a  total  abolition  of  the 
secretory  functions  of  the  stomach.  In  spite  of  this,  however, 
the  patient  may  remain  well  nourished  and  free  from  other  ill 
consequences  as  long  as  intestinal  digestion  is  normal.  The 
evil  results  produced  are  often  alone  due  to  a  failure  of  such 
compensation  on  the  part  of  the  small  intestine. 

A  purely  interstitial  inflammation  of  the  stomach  indepen- 
dent of  lesions  of  the  parenchyma  is  described  by  Hayem ;  but 


ULCER  OF  THE  STOMACH.  371 

clinically    has   no   distinctive   feature   by    which   it   can   be 
recognized. 

ULCER. 

Ulcer  of  the  stomach  may  occur  in  the  course  of  acute  and 
chronic  gastritis;  or  independently ;  not  infrequently  it  is  found 
post-mortem  when  no  symptoms  had  existed  during  life  to 
indicate  its  presence.  It  is  stated  that  in  5  per  cent,  of 
deaths  from  all  causes  either  an  open  ulcer  or  a  resulting 
cicatrix  can  be  found. 

It  is  rare  before  the  age  of  ten  years,  though  it  has  been 
met  with  in  infants  at  birth ;  it  is  much  more  frequent  in  the 
female  than  male. 

Circulatory  disturbances — arteriosclerosis,  thrombosis,  and 
embolism — are  undoubtedly  important  etiological  factors,  as  are 
likewise  general  anaemia  and  malnutrition.  The  frequent  asso- 
ciation clinically  of  hydrochloric-acid  superacidity — in  80  or 
90  per  cent,  of  cases — is  suggestive  of  autodigestion,  and  it  is 
maintained  by  many  that  without  this  excessive  acidity  of  the 
gastric  secretions  ulcer  does  not  occur.  At  least  it  must  be 
admitted  that  it  could  make  the  production  of  ulcer  easier 
when  factors  interfering  with  the  nutrition  of  the  stomach- 
wall,  at  a  given  point,  are  present;  and  also  might  subse- 
quently seriously  interfere  with  the  healing  of  such  a  lesion. 
At  first  it  was  asserted  by  Rigel  that  this  superacidity  was 
constantly  present  in  ulcer.  The  small  percentage  of  cases  in 
which  it  is  not,  might  be  accounted  for  by  an  associated  gastritis 
that  has  gone  on  to  glandular  atrophy.  On  the  other  hand, 
it  is  intelligible  that  the  superacidity  may  be  excited  by  the 
ulcer — in  a  manner  possibly  analogous  to  the  hypersecretion 
of  tears  produced  by  a  corneal  ulcer. 

Trauma  alone  cannot  produce  gastric  ulcer ;  other  factors 
are  necessary.  It  is  generally  conceded  that  gastric  ulcer 
artificially  produced  in  lower  animals  heals  promptly;  and  in 
man  pieces  of  the  mucous  membrane  have  been  torn  away  by 
suction  of  the  stomach-tube,  the  lesion  healing  without  the 
formation  of  an  ulcer.  But  if  a  high  degree  of  anemia  is 
first  produced  in  dogs  by  the  gradual  withdrawal  of  blood, 
ulcers  can  be  produced  by  various  irritants,  which  heal  very 
slowly  ;  and  so,  clinically,  ulcer  is  especially  frequent  in  chlor- 


372    DISEASES  OF  THE  G ASTRO-INTESTINAL   TRACT. 


otic  young  girls,  in  whom,  in  addition  to  the  anaemia,  a  hyper- 
chlorhydria  is  often  present. 

There  is  generally  but  one  ulcer,  though   there   may    be 
several,  often  developing  successively. 

FIG.  164. 


Two  ulcers  in  the  small  curvature  of  the  stomach, 
coat  (Warren  Museum). 

FIG.  165. 


formed  by  muscular 


Perforating  ulcer  of  the  stomach  (Warren  Museum). 

Gastric  ulcers — macroscopic  description:    The  lesion  occurs 
most  frequently  along  the  lesser  curvature  and  on  the  posterior 


ULCER   OF  THE  STOMACH. 


373 


wall  near  the  pylorus  (Fig.  164).  In  size  it  varies  from  one- 
quarter  of  an  inch  to  four  or  five  inches  in  diameter;  generally, 
however,  from  a  half  to  two  inches.  In  shape  it  is  usually 
rounded  or  oval,  and  has  a  characteristic  punched-out  appear- 
ance, especially  if  the  mucous  membrane  alone  is  involved. 
If  it  is  deeper,  the  excavation  may  be  somewhat  funnel-shaped 
by  reason  of  its  sloping  edges. 


FIG.  166. 


An  ulcer  of  the  stomach,  showing  at  its  base  the  open  orifice  of  a  vessel:  death 
from  hemorrhage  (Warren  Museum). 

If  all  the  coats  of  the  stomach-wall  are  involved,  as  often 
happens,  inflammatory  adhesions  may  bind  it  to  an  adjacent 
organ,  as  the  liver  or  pancreas,  which  thus  comes  to  form  the 
floor  of  the  ulcer. 

Microscopically,  there  is  noted  some  round-celled  infiltration 
in  the  immediate  neighborhood  of  the  ulcer.  The  walls  of 
the  adjacent  bloodvessels  are  greatly  thickened  by  an  obliter- 


374    DISEASES  OF  THE  G ASTRO-INTESTINAL  TRACT. 

ating  endarteritis — a  state  of  affairs  which  protects  largely 
against  hemorrhage. 

The  dangers  in  gastric  ulcer,  which  are  always  imminent, 
are  perforation  and  hemorrhage. 

FIG.  167. 


Hour-glass  contraction  of  stomach  (Warren  Museum,  Harvard  Medical  School). 

Perforation  (Fig.  165)  and  the  escape  of  the  stomach- 
contents  into  the  peritoneal  cavity  cause  death  immediately 
from  shock  ;  or  in  a  few  days  from  a  general  peritonitis.  This 
accident  occurs  most  frequently  when  the  ulcer  is  situated  on 


TUMORS  OF  THE  STOMACH. 


375 


the  anterior  wall  of  the  stomach.  It  may  also  take  place  into 
the  liver,  spleen,  or  pancreas,  with  resulting  abscess-forma- 
tions; or  into  the  pleura,  pericardium,  or  lungs. 

Hemorrhage,  when  a  large  vessel  is  eroded,  may  prove 
rapidly  fatal  (Fig.  166). 

Cicatrization  and  consequent  contractions  of  portions  of 
the  stomach-wall  may  cause  considerable  deformity — hour- 
glass contraction,  or  pyloric  or  cardiac  stenosis  (Fig.  167). 

TUMORS. 

Carcinoma  is  the  most  common  and  most  important  tumor 
of  the  stomach.  It  is  almost  invariably  a  primary  affection. 


FIG.  168. 


'• 


Cancer  •  a  large  fungous  growth  at  the  pylorus,  with  dilatation  and  hypertrophy  of 
the  walls  (Warren  Museum). 

Secondary  cancer  is  rare,  though  it  may  result  by  extension 
from  adjacent  organs ;  and  in  a  few  instances  there  seems  to 


376    DISEASES  OF  THE  GASTRO-INTESTINAL  TRACT. 

have  been  a  direct  implantation  of  cancer-cells  upon  the  gastric 
mucosa  from  a  primary  lesion  above — cesophageal,  lingual,  or 
facial. 

It  rarely  occurs  before  thirty  years  of  age,  though  in  a  few 
instances  it  has  been  noted  in  infants.  From  the  age  of  fifteen 
years  on,  it  rapidly  increases  in  frequency,  three-fourths  of  all 
cases  occurring  between  the  ages  of  forty  and  seventy  years. 


FIG.  169. 


Cancer  of  the  cardiac  end  of  stomach  and  oesophagus  (Warren  Museum). 

In  women,  cancer  affects  primarily  the  stomach  in  20  to 
30  per  cent,  of  cases ;  aud  in  men  in  40  to  50  per  cent.  In 
about  one-half  the  cases  the  neoplasm  is  situated  at  the  pylo- 
rus, the  posterior  wall  and  lesser  curvature  coming  next  in 
frequency. 

The  position  and  shape  of  the  stomach  are  often  altered. 


TUMORS  OF  THE  STOMACH.  377 

When  there  is  pyloric  obstruction  its  capacity  may  be  greatly 
increased  (Fig.  168);  or  much  diminished  if  such  a  con- 
dition exists  at  the  cardia,  or  if  there  is  a  diffuse  carcinoma- 
tous  infiltration  of  the  walls  of  the  organ  (Fig.  169).  If 
the  pylorus  is  not  supported  by  adhesions,  it  may  sink  to  the 
pelvis. 

Metastases  occur  in  one-half  the  cases ;  the  liver  is  in- 
volved in  over  one-third  of  them.  The  neighboring  lym- 
phatic glands,  especially  those  behind  the  lesser  curvature  of 
the  stomach,  become  converted  into  large  cancerous  nodules, 
and  the  peritoneum  is  often  involved  by  direct  extension  of 
the  tumor-formation. 

Histologically  several  varieties  of  the  neoplasm  are  recog- 
nized : 

Scirrhus  is  the  most  common,  constituting  about  75  per  cent, 
of  the  cases.  There  may  be  a  ring-like  contraction  at  the 
pylorus,  or  a  diffuse  infiltration  of  the  walls  of  the  stomach 
without  any  nodular  prominences,  which  condition  might  be 
confounded  with  a  hyperplastic  interstitial  gastritis.  Occa- 
sionally small,  flat  nodules  occur  on  the  serous  surface  over 
the  region  of  the  tumor.  If  the  mucous  membrane  ulcerates, 
which  is  rare,  it  is  only  superficial.  Scirrhus  is  almost  in- 
variably situated  at  the  pylorus. 

Encephaloid  grows  very  rapidly,  and  forms  large,  soft,  gray- 
ish-white, irregular,  papillomatous  masses,  which  project  into 
the  cavity  of  the  stomach.  It  is  so  prone  to  undergo  necrosis 
that  it  generally  presents  at  the  autopsy  as  a  bowl-shaped, 
ulcerating  depression,  with  irregular,  ragged  walls  of  varying 
height  and  thickness,  formed  by  the  surrounding  tumor-mass. 
Perforation  may  result  from  extensive  ulceration. 

Adeno-carcinoma  in  general  appearance  resembles  encepha- 
loid,  and  tends  to  undergo  extensive  ulceration  in  a  similar 
manner. 

Squamous-celled  cancer  affects  the  region  of  the  cardia,  tak- 
ing its  origin  from  the  flat  cells  of  the  resophagus. 

Colloid  carcinomata  have  a  transparent  jelly-like  appear- 
ance, due  to  the  degenerative  change  they  have  undergone. 
This  degeneration  may  affect  any  form  of  cancer,  but  more 
especially  adeno-carcinoma. 


378    DISEASES  OF  THE  G ASTRO-INTESTINAL   TRACT. 


THE  INTESTINES. 
Congenital  Deformities  and  Displacements. 

Absence  of  the  whole,  or  large  parts,  of  the  intestinal  tract 
is  sometimes  met  with  in  monstrosities.  Lesser  developmental 
defects  are  not  uncommon.  The  anus  may  be  wanting — 
imperforate  anus — and  likewise  the  rectum  and  lower  part  of 
the  colon.  MeckeVs  diverticulum  (Fig.  170)  is  a  remnant  of 


FIG.  170. 


Meckel's  diverticulum  (Dennis). 

the  omphalo-mesenteric  duct  of  foetal  life.  It  is  a  cylindrical 
appendage,  of  the  same  structure  as  the  small  intestine,  and 
arises  from  the  latter,  opposite  the  mesenteric  attachment, 
about  a  meter  above  the  ileo-csecal  valve.  Such  diverticula 
are  sometimes  the  cause  of  intestinal  obstruction  (Fig.  171). 
The  caecum  and  ascending  colon  are  sometimes  situated  on 


ACQUIRED  DEFORMITIES  AND  DISPLACEMENTS.  379 

the  left  side,  and  the  descending  colon  and  sigmoid  flexure  on 
the  right.  The  transverse  colon  may  be  entirely  absent,  the 
ascending  and  descending  colon  lying  side  by  side. 


FIG.  171. 


Internal  strangulation  by  a  diverticulum  (Warren  Museum). 

Acquired  Deformities  and  Displacements. 

Hernia  is  a  term  by  which  is  generally  understood  a  pro- 
trusion of  the  intestine  through  a  natural  but  abnormally 
dilated  opening  in  the  abdominal  wall.  It  pushes  in  front  of 
itself  the  peritoneum,  which  thus  forms  the  sac  of  the  hernia. 

Strangulation  is  the  most  serious  result  of  hernia,  and  occurs 
when  the  gut  is  so  constricted  or  compressed  that  it  is  no  longer 


380    DISEASES  OF  THE  G ASTRO-INTESTINAL   TRACT. 

pervious.  By  reason  of  the  interference  with  its  blood- 
supply,  if  the  constriction  is  not  relieved,  gangrene  sooner 
or  later  ensues. 

Volvulus  is  another  frequent  cause  of  intestinal  obstruction. 
There  is  either  a  twist  of  the  bowel  on  its  long  axis,  or,  more 
frequently,  a  loop  of  intestine  is  twisted  around  its  mesenteric 
attachment.  The  sigmoid  flexure  is  the  most  frequent  seat 
of  its  occurrence. 

Intussusception,  or  invagination,  is  more  frequent  in  chil- 
dren than  in  adults,  occurring  usually  at  the  ileo-csecal  valve. 
One  part  of  the  intestine  slips  over  another,  the  length  of  the 
invagination,  which  is  nearly  always  downward,  varying  from 
a  few  inches  to  several  feet  (Fig.  172).  Thus  the  caecum  and 

FIG.  172. 


J 


" • I —-*"•••  ""••-  .  _';  ,;•  ^.^"^ 

Ileo-csecal  intussusception  of  minor  degree.      To  the  right  is  seen  the  appendix 
vermiformis  just  about  to  be  swallowed  (Hutchinson). 


lower  part  of  the  ileum  may  be  pushed  into  the  colon  until 
the  ileo-csecal  valve  even  reaches  the  rectum.  Gangrene  and 
a  fatal  peritonitis  are  the  usual  termination. 

Inflammations. 

Inflammatory  processes  may  involve  more  or  less  the  entire 
length  of  the  intestinal  tract — entero-oolitis — or  be  more  par- 
ticularly limited  to  one  of  its  subdivisions,  suggesting  the 
terms  duodenitis,  colitis,  ileo-colitis,  typhlitis,  proctitis,  etc. 

Enteritis — inflammation    of    the     small    intestine — is    an 


ACUTE  COLITIS.  381 

exceedingly  frequent  affection,  the  most  prominent  clinical 
feature  of  which  is  diarrhoea.  The  watery  consistency  of  the 
stools  is  due,  not  so  much  to  the  inflammatory  serous  exuda- 
tion, as  to  the  increased  peristalsis,  which  permits  of  less  time 
for  the  abstraction  of  the  fluid  constituents  of  the  intestinal 
contents. 

The  inflammatory  process  is  caused  by  improper  food,  espe- 
cially that  in  which  poisonous  alkaloids  have  been  formed 
during  putrefactive  changes  ;  also  by  inorganic  poisons,  like 
arsenic  and  antimony ;  and  it  may  occur  secondarily  in  the 
course  of  various  infectious  diseases. 

Lesions :  The  mucous  membrane  is  red  and  swrollen,  often 
covered  with  mucus;  and  here  and  there  maybe  small  hemor- 
rhagic  spots.  The  solitary  and  agminated  lymphatic  follicles 
are  swollen,  and  appear  as  small,  dull  gray  prominences  upon 
the  mucous  surface ;  small  pitted,  so-called  follicular  ulcers 
result  if  these  lymphatic  glands  undergo  necrosis.  In  severe 
cases  the  raesenteric  glands  are  enlarged.  When  the  inflam- 
matory process  becomes  chronic,  the  rnuscularis  is  in- 
volved, as  in  gastritis,  and  often  much  hypertrophied.  Some- 
times polypoid  elevations  are  produced  by  proliferation  of 
glandular  elements.  In  the  later  stages  there  may  be  atrophy 
of  the  mucous  membrane  alone,  or  involving,  in  addition,  the 
muscularis. 

A  duodenitis  may  be  associated  with  an  inflammation  of  the 
stomach.  It  is  exceedingly  liable  to  produce  an  obstruction 
of  the  common  bile-duct  by  inflammatory  swelling  of  the 
mucosa  and  accumulation  of  mucus,  thus  giving  rise  to  reten- 
tion of  bile  and  an  obstructive  or  catarrhal  jaundice. 

Acute  colitis  is,  in  the  great  majority  of  instances,  associated 
with  the  condition  recognized  clinically  as  dysentery.  Sporadic 
cases  result  from  ingestion  of  tainted  food,  from  mercury  and 
other  poisons.  The  infectious  nature  of  the  epidemic  form 
naturally  suggests  itself.  The  amoeba  coli,  a  unicellular  amoe- 
boid body,  measuring  twenty  to  fifty  microns  in  diameter,  is 
found  not  only  in  the  stools,  but  also  in  the  intestinal  wall 
adjacent  to  the  dysenteric  ulcers,  and  in  the  pus  in  hepatic 
abscesses  secondary  to  dysentery.  Typical  dysentery  has 


382    DISEASES  OF  THE  OASTRO-INTESTINAL   TRACT. 

been  produced  in  lower  animals  by  the  injection  of  dysenteric 
stools  into  their  intestines. 

The  severity  of  the  lesions  noted  varies  greatly.     In  mild 
cases  the  mucous  membrane  is  swollen  and  hypersemic,  and 


FIG.  173. 


Appendix  containing  biliary  calculus  (Museum,  Carnegie  Laboratory).   1,  biliary 

calculus. 

covered  with  tenacious  mucus.  The  solitary  follicles  are 
enlarged,  and  petechial  hemorrhages  are  often  seen.  At  a 
later  stage  and  in  more  severe  cases  these  follicles  undergo 


ACUTE  COLITIS. 


383 


necrosis  ;  the  resulting  ulcers  may  be  superficial,  or  deep  and 
ragged  in  outline,  spreading  rapidly,  so  that  there  is  but  little 
of  the  mucous  membrane  unaffected.  In  many  cases  the 

FIG.  174. 


Appendix  containing  two  fecal  concrements :  case  of  perforative  appendicitis,  the 
perforation  opposite  the  distal  concrement  (Museum,  Carnegie  Laboratory). 

mucous  membrane  is  covered  with  a  grayish  or  brownish 
pseudo-membrane,  either  in  isolated  patches  or  less  frequently 
as  a  uniform  coating — diphtheritic  or  croupous  dysentery. 


384    DISEASES  OF  THE  GASTRO-INTESTINAL   TRACT. 

Fi«.  175. 


Suppurative  appendicitis,  abscess  of  appendicular  wall,  perforation,  localized  sup- 
purative  peritonitis;  2,  ruptured  abscess  of  wall ;  3,  extension  of  a  suppurative 
focus  (Museum,  Carnegie  Laboratory). 

Sloughs  of  varying  depth  and  sometimes  of  very  considerable 
size  may  form,  and,  on  separating,  leave  behind  ragged  ulcers. 


APPENDICITIS. 


385 


Chronic  inflammation  may  succeed  the  acute.  In  some  cases 
the  inflammatory  process  is  limited  to  the  rectum — proctitis. 
Appendicitis — inflammation  of  the  vermiform  appendix — is 
now  recognized  as  the  cause  of  the  set  of  symptoms  which 
were  at  one  time  attributed  to  inflammation  of  the  caecum — 
typhlitis.  On  laying  open  the  appendix,  faecal  concretions 
are  sometimes  found,  to  which  an  etiological  significance  has 
been  attributed  (Figs.  173  and  174);  but  they  are  quite  as 


FIG.  1 


Funnel-shaped  csecum  and  appendix,  gangrenous  appendicitis  :  1,  fecal  concre- 
ment;  2,  mesenteriolum  ;  3,  appendix,  situated  behind  and  to  inner  side  of 
caecum  ;  4,  ilio-csecal  junction  (Hartley). 

likely  the  result  as  the  cause  of  the  condition,  and  formed  by 
accumulations  of  mucus,  desquamated  epithelial  cells  and 
other  inflammatory  products.  Undoubtedly  the  common  colon 
bacillus,  which  is  normally  present,  plays  an  important  part, 
multiplying  rapidly  and  gaining  new  virulence  in  the  favor- 
able nidus  produced  by  the  inflammatory  process.  The  entire 
wall  of  the  appendix  may  be  involved,  or  the  lining  mucous 
membrane  alone.  Necrosis  and  ulceration  may  result 


n 


25—  Hist. 


386    DISEASES  OF  THE  G ASTRO-INTESTINAL   TRACT. 

perforation  and  localized  purulent  collections,  or  a  general 
septic  peritonitis.  Not  infrequently  the  whole  organ  becomes 
almost  immediately  gangrenous  (Figs.  175  and  176). 

Specific  Inflammations  of  the  Intestines. 

Asiatic  cholera  is  an  acute  infectious  disease  characterized 
by  an  intense  inflammation  of,  and  a  copious  serous  exudate 
from,  the  small  and  large  intestine ;  due  to  the  spirillum 
cholera?,  first  described  by  Koch.  Clinically,  also,  the  main 
features  of  the  disease  are  referable  to  the  intestinal  tract,  the 
constitutional  disturbances  being  due  to  the  absorption  into 
the  general  circulation  of  toxins  produced  by  the  micro- 
organisms there  localized.  The  mucous  membrane,  particu- 
larly in  the  lower  part  of  the  ileum,  is  swollen,  congested,  and 
frequently  the  seat  of  ecchymoses ;  the  solitary  and  agminated 
lymphatic  follicles  are  often  swollen,  as  may  be  likewise  the 
mesenteric  glands.  The  bowel  is  distended  as  if  paralyzed, 
and  filled,  often  with  large  quantities,  of  a  serous  transuda- 
tion  containing  small  white  flakes  of  desquamated  and  de- 
generated epithelial  cells,  similar  to  the  characteristic  "  rice- 
water"  dejections. 

Later  in  the  disease,  in  some  epidemics,  the  mucous  mem- 
brane may  be  ulcerated  or  covered  by  a  pseudo-membrane, 
the  colon  presenting  an  appearance  similar  to  that  in  dysen- 
tery— possibly  the  result  of  secondary  infections.  Outside  of 
the  intestinal  tract  one  of  the  most  marked  features  of  the 
disease  is  the  pronounced  thickening  of  the  blood  due  to  the 
enormous  serous  transudations. 

The  heart,  liver,  spleen,  and  kidneys  may  be  the  seat  of 
parenchymatous  degenerations  characteristic  of  other  toxaemias 
as  well,  however,  and  in  no  way  distinctive  of  this  disease. 

Typhoid  fever  is  an  acute  infectious  disease  produced  by  the 
bacillus  of  Eberth,  the  characteristic  lesions  being  almost 
entirely  confined  to  the  lymphadenoid  structures  of  the  lower 
part  of  the  ileum  and  upper  part  of  the  colon.  Contaminated 
water  or  milk  is  the  chief  source  of  infection. 

The  morbid  changes  in  typhoid  fever  may  begin  as  a  diffuse 
inflammation  of  the  intestinal  mucosa,  but  almost  immediately, 
at  least  within  twenty-four  hours,  the  solitary  follicles  and 


TYPHOID  FEVER. 


387 


a  quarter  of  an  inch  thick. 


FIG.  177. 


Swelling  of  Peyer's  patches  and  solitary 
glands  of  the  intestine,  as  seen  in 
typhoid  fever  (Green). 


Peyer's  patches  become  infiltrated,  intensely  congested,  swollen, 
and  project  into  the  lumen  of  the  intestine.  The  largest 
patches  may  be  as  much  as 
The  solitary  follicles  vary  in 
size  from  that  of  a  pin  point 
to  that  of  a  pea  (Fig.  177). 
By  the  end  of  the  first  week 
the  number  of  patches  and 
follicles  involved  is  about  as 
large  as  it  will  probably  be- 
come, and  the  stage  of  in- 
flammatory infiltration  and 
hypet-plasia  has  reached  its 
height.  These  changes  may 
affect  only  a  few  patches  and 
follicles  in  the  neighborhood 
of  the  caecum  or  involve  the 
entire  intestinal  tract. 

Generally  the  swollen  solitary  follicles  are  not  so  numerous 
as  the  swollen  Peyer's  patches,  though  in  some  cases  they  are 
more  prominent,  the  patches  being  but  little  affected.  Cases 
of  undoubted  typhoid  have  been  reported  in  which  all  intesti- 
nal lesions  were  absent. 

Resolution  now  slowly  takes  place  through  the  absorption 
of  the  inflammatory  products  ;  or  a  greater  or  less  number  of 

patches,  according  to  the  severity 
of  the  case,  undergo  necrosis  as  the 
result  of  interference  with  the  blood- 
supply  by  the  pressure  of  the  sur- 
rounding excessive  infiltration.  The 
patches  become  less  congested,  gray- 
ish in  color,  with  possibly  a  yel- 
lowish or  brownish  necrotic  centre. 
When  the  slough  separates  there  is 
left  behind  a  large  ragged  ulcer, 
which  generally  involves  only  the 
mucous  membrane,  but  may  extend 
even  through  the  muscularis  and 
rarely  through  the  serosa,  thus  producing  perforation. 
Hemorrhage  may  also  occur  with  the  separation  of  the  slough. 


FIG.  178. 


A  typhoid  ulcer  of  the 
intestine  (Green). 


388    DISEASES  OF  THE  G ASTRO-INTESTINAL  TRACT. 

The  resulting  ulcers  usually  conform  to  the  size  and  shape 
of  the  patch  involved  (Figs.  178  and  179)  ;  especially  in  the 

FIG.  179. 


A  typical  ulcer  of  the  intestine  (diagrammatic),  showing  the  undermined  edges  of 
the  ulcer  and  the  slough  still  adherent  :  a,  epithelial  lining;  b,  submucous 
tissue  ;  c,  muscular  coat ;  d,  peritoneum  (Green). 

lower  part  of  the  ileum,  however,  the  ulcers  are  liable  to 
coalesce,  and  thus  involve  extensive  areas  of  the  mucous 
membrane.  The  solitary  follicles  undergo  necrosis  in  a  similar 
manner,  resulting  in  the  formation  of  rounded  ulcers.  By 
the  end  of  the  third  week  this  stage  of  ulceration  is  generally 
complete,  and  during  the  fourth  week  cicatrization  is  in  prog- 
ress, finally  leaving  behind  thin,  transparent,  flexible  scars, 
which  often  can  be  recognized  years  afterward ;  the  lymph- 
atic elements  are  not  replaced. 

Microscopically  the  swelling  of  the  patches  and  follicles  is 
found  to  be  due  mainly  to  an  active  proliferation  of  their 
lymphoid  cells;  a  few  larger  epithelioid  cells  are  usually 
present. 

Coincident  with  these  intestinal  lesions  of  typhoid,  the 
mesenteric  glands,  in  relation  to  the  areas  most  affected, 
become  swollen  from  a  similar  inflammatory  hyperplasia,  and 
to  an  extent  in  proportion  to  the  severity  of  the  intestinal 
lesion. 

Enlargement  of  the  spleen  is  also  almost  constantly  present — 
produced  by  its  congestion  and  an  increase  of  its  lymphoid 
elements ;  large  epithelioid  cells  are  often  present,  as  in  the 
intestinal  lesions  and  mesenteric  glands,  which  are  actively 
phagocytic,  frequently  having  encysted  within  them  fragments 
of  red  corpuscles. 

The  spleen,  as  well  as  the  liver  and  kidneys,  are  often  the 
seat  of  necrotic  foci.  The  typhoid,  bacilli  can  usually  be 
demonstrated  in  large  clumps,  in  properly  stained  sections  of 
the  spleen  (Figs.  180  and  181),  though  the  whole  organ  may 
possibly  be  cut  up  in  a  vain  search  for  them.  They  are  also 
present  in  the  intestinal  lesions,  mesenteric  glands,  liver  and 
kidneys,  in  the  dejecta,  and  can  sometimes  be  found  in  the 


TYPHOID  FEVER. 

FIG.  180. 

. 


389 


;  ..^  ^  ^ 


Human  spleen,  tenth  day  of  enteric  fever  (Charcot). 
FjG.  181. 


, 


VX5N 


Human  liver,  tenth  day  of  enteric  fever  (Charcot). 

blood.  In  the  absence  of  a  leukocytosis,  the  blood  of  typhoid 
presents  a  marked  clinical  contrast  to  the  blood  in  other  acute 
infectious  diseases. 


390    DISEASES  OF  THE  G ASTRO-INTESTINAL   TRACT. 

The  lesions  of  other  organs  are  in  no  way  characteristic  of 
the  disease.  Parenchymatous  or  granular  degenerations  are 
found  in  all  toxaemias  of  sufficient  degree  and  duration  ;  the 
liver,  kidneys,  and  heart-walls  are  so  affected. 

Inflammation  of  the  pericardium,  endocardium,  or  myo- 
cardium is  not  uncommon. 

A  peculiar  waxy  or  hyaline  degeneration,  which  may  occur 
also  in  other  infectious  diseases,  involves  the  voluntary  muscles, 
the  fibres  being  converted  into  a  homogeneous,  colorless,  shin- 
ing mass  resembling  amyloid  degeneration,  but  not  giving  its 
characteristic  reaction  with  iodine  and  sulphuric  acid,  and 
affecting  most  frequently  the  abdominal  muscles,  adductors 
of  thighs,  the  pectorals,  the  diaphragm,  and  sometimes  the 
myocardium. 

Bronchitis,  lobar  and  lobular  pneumonia  are  frequent  com- 
plications ;  gangrene  of  the  lungs  a  rare  one.  Occasionally 
there  is  an  inflammation  of  the  parotid  gland,  which  tends  to 
terminate  in  abscess-formation.  A  grave  peritonitis  is  gener- 
ally the  result  of  perforation,  though  it  may  have  its  starting- 
point  in  a  deep  ulcer  which  involves,  but  does  not  perforate 
the  serosa ;  or  it  may  be  due  to  the  inflammation  involving 
the  mesenteric  glands. 

An  obliterating  endarteritis  may  occur,  especially  during 
convalescence,  leading  to  thrombosis  and  necrosis  of  the  tissue 
supplied.  Thrombosis  may  also  occur  in  the  veins,  especially 
the  femoral,  rarely  in  the  cerebral  sinuses. 

An  orchitis  occurring  during  convalescence,  and  frequently 
terminating  in  suppuration,  has  been  described. 

Tuberculosis,  though  scarcely  ever  noted  in  the  oesophagus 
or  stomach,  very  frequently  affects  the  intestinal  tract — in  fact, 
is  one  of  the  most  common  pathological  conditions  met  in  the 
intestine.  While  not  necessarily  confined  to  the  lymphadenoid 
tissue,  these  structures  are  especially  involved,  the  lesions 
being  most  numerous  in  the  lower  part  of  the  ileum  and  in 
the  colon.  It  may  be  primary — rarely  in  adults,  though  some- 
what more  frequently  in  infants ;  generally  it  is  secondary  to 
tuberculosis  of  the  lungs,  and  the  result  of  swallowing  infected 
sputum. 

The    tubercle    appears    beneath    the    mucous    membrane 


SYPHILITIC  ULCERATION.  391 

as  a  grayish  nodule ;  soon  it  becomes  yellowish  from  rapidly 
advancing  caseation,  and  finally  breaks  down  completely. 

The  resulting  ulcer  generally  involves  the  muscularis ;  its 
floor  is  rough  and  nodular,  from  the  presence  of  small  tuber- 
cles, which  can  be  seen  beneath  the  serosa  externally  (Fig. 
182).  The  ulcers  at  first  resemble  somewhat  those  of 

FIG.  182. 


Tubercular  ulcer  of  the  intestine  (Kaufmann).  The  cavity  of  the  ulcer  was  formed 
through  disintegration  and  removal  of  the  cheesy  matter  formed  in  the  earlier 
tubercles.  Now  the  base  of  the  ulcer  is  formed  by  necrosed  and  cheesy  ma- 
terial, beneath  which  eight  or  nine  distinct  tubercles  are  distinguishable,  those 
in  the  centre  extending  into  the  muscular  coat  of  the  intestine.  The  infection 
has  also  extended  into  the  lymphatics  beneath  the  serous  coat,  where  three 
tubercles  can  be  seen. 

typhoid  fever ;  but  soon,  as  the  result  of  breaking  down  of 
other  newly-forming  tubercles  at  their  margins,  the  ulceration 
extends  beyond  the  limits  of  the  lymphoid  tissue,  no  longer 
conforming  to  the  size  and  shape  of  these  structures.  Fresh 
tubercles  being  formed  in  this  way  along  the  line  of  the  lym- 
phatic vessels,  which  run  toward  the  mesentery,  the  long  axis 
of  the  ulcer  becomes  transverse,  a  complete  ring  of  mucous 
membrane  being  destroyed,  in  some  cases,  in  this  manner — 
annular  ulcer.  The  border  of  the  ulcer,  like  its  base,  is  infil- 
trated here  and  there  with  small  tubercular  nodules.  On  the 
external  serous  surface  radiating  lines  are  noted,  extending 
from  the  base  of  the  ulcer  around  the  intestine  toward  the 
mesentery,  marking  the  tubercular  infiltration  of  the  subserous 
lymphatics.  Perforation  is  rare,  owing  to  this  infiltration  and 
thickening  of  the  tissues.  The  corresponding  mesenteric 
glands  are  generally  affected.  If  the  ulcer  heals,  which  is 
infrequent,  a  puckered  scar  and  possibly  cicatricial  deformities 
remain. 

Microscopically -,  the  characteristic  feature  is  the  presence  of 
small  tubercles  in  the  floor  and  walls  of  the  ulcer. 

Syphilitic   ulceration  of  the  solitary  follicles   and   Fever's 
patches  of  the  small  intestine  sometimes  occurs  in  infants. 


392    DISEASES  OF  THE  G ASTRO-INTESTINAL   TRACT. 

In  adults,  though  the  small  intestine  and  colon  may  rarely  be 
involved,  the  rectum  is  the  part  of  the  intestinal  tract  most 
frequently  affected. 

TUMORS. 

Carcinoma  is  the  most  important  and  most  frequent  tumor 
affecting  the  intestinal  tract,  though  not  nearly  as  common  as 


FIG.  183. 


Alv 


Section  showing  degenerative  changes  in  carcinoma  of  the  rectum  :  Me,  mucosa ; 
Smc,  submucosa  ;  M.  int,  inner  muscular  fibres  (circular) ;  M.  ext,  outer  muscular 
fibres  (longitudinal);  V,  bloodvessels ;  Ad,  margin  of  growth,  showing  hyper- 
trophied  follicles  and  submucous  tissue  infiltrated  with  new  adenoid  tissue ; 
X,  mucus;  Ca,  ulcerated  portion  of  the  superficial  surface  of  the  growth  ;  XX, 
remains  of  gland-follicles  still  recognizable ;  Alv,  glandular  recesses  dilated  into 
distinct  alveoli;  Col,  large  alveoli  filled  with  mucoid  or  colloid  material;  Str. 
stroma;  Met,  adenoid  proliferation  infiltrating  deeper  layers  of  bowel-wall 
(Esmarch). 

in  the  stomach.  In  the  small  intestine  it  is  rare,  the  duode- 
num near  the  opening  of  the  bile-duct  being  the  point  at 
which  it  usually  is  situated.  More  frequently  it  occurs  in  the 


LIVER — ACUTE   YELLOW  ATROPHY.  393 

rectum,  the  caecum,  and  flexures  of  the  colon.  It  usually  pre- 
sents as  a  solitary,  soft,  often  ulcerating,  fungous  mass,  which 
projects  into  the  lumen  of  the  intestine  (Fig.  183). 

Microscopically,  the  adeno-carcinoma  or  cylindrically-celled 
cancer  is  the  variety  most  frequently  noted. 

Connective-tissue  tumors  are  not  often  found  in  the  intestinal 
tract. 

THE  LIVER. 

PASSIVE  HYPER^IMIA. 

Passive  hyperaemia  is  produced  by  some  obstruction  to  the 
circulation  through  the  hepatic  vein,  as  by  a  large  pleuritic 
effusion;  intrathoracic  tumors,  cirrhosis  of  the  lungs;  and 
especially  valvular  disease  of  the  heart.  At  first  the  liver  is 
often  considerably  enlarged  ;  on  section,  it  has  a  peculiar 
mottled  or  nutmeg  appearance,  the  darker  congested  areas 
around  the  central  hepatic  vein  of  the  lobule  contrasting 
markedly  with  the  lighter  periphery,  which  may  be  yellowish 
or  yellowish-white  from  advancing  fatty  degeneration.  At  a 
later  stage  the  liver  is  decreased  in  size,  from  atrophy  of  the 
parenchyma-cells  produced  by  the  excessive  pressure  of  the 
blood  ;  and  there  may  be  very  considerable  hyperplasia  of  the 
connective  tissue,  giving  the  organ  a  slightly  roughened  or 
uneven  surface. 

Microscopically,  the  central  hepatic  vein  and  surrounding 
capillaries  are  greatly  dilated  and  engorged  with  blood.  In 
the  centre  of  the  lobule  the  rows  of  liver-cells  between  the 
dilated  capillaries  are  entirely  atrophied.  In  the  peripheral 
zone  of  the  lobule  there  is  often  an  advanced  fatty  degenera- 
tion. 

ACUTE  YELLOW  ATROPHY. 

Acute  yellow  atrophy  of  the  liver  occurs  as  an  independent 
specific  disease ;  or  secondarily  to  phosphorus-poisoning, 
typhoid  fever,  puerperal  septicaemia,  and  other  infectious 
diseases.  As  an  independent  affection,  however,  it  is  ex- 
ceedingly rare. 

Anatomically,  the  characteristic  feature  of  the  disease  is  the 


394    DISEASES  OF  THE  GASTRO-TNTESTINAL   TRACT. 

rapid  diminution  of  the  liver  to  one-half,  even  one-quarter  its 
natural  size,  as  the  result  of  extensive  degenerative  changes 
of  the  parenchyma.  This  reduction  in  size  affects  mainly  its 
vertical  diameter,  the  organ  being  flattened  out  against  the 
spinal  column  to  a  few  centimetres  in  thickness,  and  almost 
concealed  by  the  diaphragm  and  superimposed  coils  of  intes- 
tine. It  is  ochreous-yellow  in  color,  soft  and  flabby,  in 
places  almost  pulpy  ;  or  the  yellow  alternates  with  relatively 
firmer  red  patches — so-called  red  atrophy — giving  the  surface 
a  mottled  appearance,  especially  on  section.  The  capsule  is 
wrinkled  to  such  an  extent  that  it  can  be  picked  up  by  the 
fi  ngers. 

Microscopically,  the  outlines  of  the  lobules  are  indistin- 
guishable. The  liver-cells  are  in  various  stages  of  degenera- 
tion or  necrosis ;  in  the  yellow  areas  their  outlines  may  be 
preserved,  but  their  protoplasm  contains  numerous  fat-globules 
and  granules  of  yellow  pigment ;  or  the  cells  may  be  entirely 
replaced  by  a  detritus  of  yellow  pigment ;  and  irregular  col- 
lections of  fat- globules,  only  the  connective- tissue  framework 
of  the  liver  remaining.  In  the  red  areas  the  cells  are  entirely 
wanting,  the  tissue  being  colored  by  an  infiltration  with  hema- 
togenous  pigments. 

INFLAMMATIONS. 

Acute  purulent  inflammation  (Fig.  184)  of  the  liver  results 
in  the  formation  of  one  or  more  circumscribed  collections  of 
pus.  The  avenues  open  to  infection  by  the  invasion  of  va- 
rious micro-organisms  are  numerous :  the  hepatic  artery, 
portal  vein,  bile-duct,  arid  the  patent  umbilical  vein  in  infants ; 
or  infection  may  extend  from  neighboring  organs  through  the 
lymphatics.  The  bacillus  coli  communis,  staphylococci,  and 
streptococci  are  the  organisms  which  have  been  most  frequently 
found  associated  with  these  purulent  inflammations  of  the 
liver;  in  cases  following  dysentery  the  amoeba  coll  is  fre- 
quently found  in  the  pus. 

The  single  large  so-called  tropical  abscess  is  a  very  common 
affection  in  the  torrid  zone,  often  as  a  sequela  of  dysentery. 
It  may  be  associated  with  the  presence  of  tumors  or  parasites 
in  other  cases.  The  abscess  is  generally  situated  in  the  right 
lobe,  and  varies  in  size  from  a  man's  fist  to  that  of  a  child's 


LIVER— TROPICAL  ABSCESS. 


395 


head ;  an  entire  lobe  or  even  the  whole  organ  may  be  in- 
volved. It  may  rupture  into  the  pleural  or  peritoneal  cavi- 
ties, into  the  stomach,  intestine,  or  externally  through  the 


FIG.  184. 


Abscess  of  liver  in  a  case  of  pysemic  infection  through  a  wound  in  the  appendix 
vermiformis  caused  by  lodgement  of  a  pin  (Loomis  and  Thompson). 

abdominal  wall.  As  to  the  mode  of  their  formation,  but  little 
is  known  ;  undoubtedly  they  often  result  from  the  confluence 
of  smaller  abscesses. 

The  walls  of  the  abscess  are  ragged — shreds  of  necrotic  liver- 


396    DISEASES  OF  THE  GASTRO-INTESTINAL   TRACT. 

tissue  projecting  into  the  cavity ;  there  is  no  trace  of  a  mem- 
brane. The  contents  of  the  cavity  have  an  offensive,  sickly 
odor ;  are  thick  and  creamy  like  pus,  or  thin  and  reddish- 
brown  from  the  admixture  of  extravasated  blood. 

Microscopically,  this  fluid  is  found  to  contain  pus-cells,  frag- 
ments of  degenerated  liver-cells,  shreds  of  connective  tissue, 
and  red  blood-corpuscles.  The  abscess-wall  shows  but  little, 
if  any,  inflammatory  infiltration. 

Small  metastatic  abscesses,  varying  in  size  from  a  pin-head 
to  that  of  a  walnut,  are  sometimes  present  to  the  number  of 
forty  or  fifty,  scattered  throughout  the  liver.  They  occur  in 
the  course  of  pyaemia  and  septic  inflammations  of  parts  tribu- 
tary to  the  portal  vein. 

Microscopically :  In  the  early  stage  of  their  formation  there 
is  noted  an  area  of  necrosis,  the  centre  of  which  may  have 
become  simply  a  granular  detritus  arising  from  the  disinte- 
gration of  the  liver-cells.  Surrounding  the  necrotic  area  is  a 
zone  of  more  or  less  marked  inflammatory  infiltration. 

Chronic  interstitial  inflammation  or  cirrhosis  of  the  liver  is 
also  known  as  "  gin-drinkers' "  liver,  for  at  least  two-thirds 
of  the  cases  are  due  to  chronic  alcoholism.  Certain  acute  in- 
fectious diseases,  chiefly  cholera,  typhoid,  and  intermittent 
fever,  are  supposed  by  some  to  be  important  etiological  fac- 
tors. Among  chronic  infectious  diseases,  syphilis  is  an  un- 
doubted cause  of  cirrhosis.  Gout  and  rheumatism  seem  to  be 
responsible  for  some  cases.  Experimentally,  the  condition  has 
been  produced  in  lower  animals  by  chronic  poisoning  with 
phosphorus  and  cantharides.  Though  in  most  instances 
hematogenous  in  its  origin,  in  some  it  is  biliary,  due  to  an 
obstruction  of  the  bile-ducts. 

In  the  early  stages  the  liver  may  be  considerably  hyper- 
trophied  ;  finally,  however,  in  the  great  majority  of  cases  it  is 
reduced  in  size  even  to  one-third  the  normal.  The  longer  the 
duration  of  the  disease  the  greater  the  atrophy,  and  the  tougher 
and  more  leathery  the  consistence  of  the  organ.  Its  surface 
is  rendered  irregular  by  numerous  nodular  projections  vary- 
ing in  size  from  a  millet-seed  to  that  of  a  hazclnut.  The 
yellow  color  of  these  granulations  suggested  to  Lacnnec  the 
term  cirrhosis  (from  xifipoz,  yellow).  On  section  a  grating 
sound  is  emitted,  and  the  almost  cartilaginous  consistence  of 


HYPERTROPHIC  OR  BILIARY  CIRRHOSIS.          397 

the  organ  may  be  noted  ;  a  network  of  connective-tissue  bands, 
running  in  all  directions — extensions  from  the  thickened 
fibrous  capsule  of  Glisson — is  seen,  which  divides  the  paren- 
chyma into  small  islets  corresponding  in  size  to  the  surface- 
granulations.  The  yellow  bile-stained  groups  of  lobules  and 
pink  interlobular  fibrous  tissue  gives  the  cut  surface  a  mot- 
tled and  granular  appearance. 

Microscopically,  the  chief  characteristic  is  the  chronic  diffuse 
inflammatory  hyperplasia  of  the  interstitial  connective  tissue, 
and  resulting  atrophy  of  the  parenchyma  of  the  liver,  at  least 
a  numerical  atrophy,  as  the  hepatic  cells  which  remain  in  the 
projecting  granulations  or  nodules  frequently  undergo  a  com- 
pensatory hypertrophy  to  twice  their  normal  size.  As  long 
as  the  hyperplasia  is  in  excess  of  the  atrophic  changes  the 
organ  is  enlarged.  As  the  newly  formed  connective  tissue 
becomes  more  sclerotic,  compressing  the  cells  of  the  lobules 
and  the  vessels  from  which  they  obtain  their  nourishment, 
the  atrophy  which  is  produced,  both  by  direct  pressure  and 
interference  with  the  blood-supply,  sooner  or  later  results  in 
a  reduction  in  the  size  of  the  organ.  The  yellow  appearance 
of  the  nodules  is  in  part  due  to  the  obstruction,  produced  by 
the  hyperplastic  connective  tissue,  to  the  discharge  of  bile 
from  the  bile-capillaries  into  the  interlobular  ducts;  and  in 
addition  there  is  generally  an  excessive  accumulation  of  fat 
in  the  liver-cells,  resulting  not  only  from  the  lessened  blood- 
supply,  but  also  probably  from  the  fact  that  there  are  fewer 
cells  in  which  to  store  the  fat  normally  present  in  the  liver. 

The  pathological  changes  begin  as  a  round-celled  infiltra- 
tion of  the  interlobular  connective  tissue.  Through  the  fur- 
ther development  of  these  migrated  and  proliferating  cells 
dense  fibrous  tissue  is  formed,  the  cellular  character  of  which 
is  finally  almost  entirely  lost,  so  that  it  comes  to  resemble 
cicatricial  tissue  (Fig.  185).  The  result  of  the  obliteration  of 
the  portal  capillaries  is  engorgement  of  the  portal  circulation, 
the  most  important  aspect  of  which  clinically  is  the  enormous 
serous  transudation  into  the  peritoneal  cavity,  which  is  called 
ascites. 

Hypertrophic  or  biliary  cirrhosis  differs  from  the  ordinary 
atrophic  variety,  in  that  the  connective-tissue  hyperplasia, 
which  is  interlobular  or  monolobular,  does  not  have  the  same 


398    DISEASES  OF  THE  G ASTRO-INTESTINAL  TRACT. 

tendency  toward  sclerosis  and  contraction,  and  as  a  result  the 
atrophic  changes  in  the  parenchyma  are  not  so  marked.  The 
term  biliary  is  suggested  by  the  fact  that  it  generally  arises 


Atrophic  cirrhosis  of  liver,    a,  acini,  in  parts  much  diminished  in  size;  b,  inter- 
acinous  bands  of  connective  tissue.    X  250  (Schmaus). 

in  connection  with  inflammation  or  obstruction  of  the  bile- 
ducts. 

The  inflammatory  hyperplasia  begins  around  the  inter- 
lobular  bile-ducts,  instead  of  around  the  branches  of  the  portal 
vein.  Experimentally,  a  monolobular  cirrhosis  can  be  pro- 


LIVER— PRIMARY  CARCINOMA.  399 

duced  by  obstruction  of  the  bile-ducts,  though  in  man  it  is  by 
no  means  a  constant  accompaniment  of  such  an  obstruction. 
In  some  cases  formation  of  new  bile-capillaries  is  observed. 
The  organ  is  enlarged,  its  surface  finely  granular,  and  on 
section  yellow  to  dark  green  bile-stained  patches  are  noted. 
Clinically,  jaundice  is  nearly  always  present,  due  to  the 
obstruction  of  the  bile-ducts  by  the  newly  forming  connective 
tissue;  the  portal  vein  is  not  obstructed  as  in  the  atrophic 
variety,  so  that  ascites  is  generally  absent. 

The  specific  granulomata :  Syphilitic  lesions  of  the  liver 
occur  generally  as  a  diffuse  cirrhosis,  resembling  the  ordinary 
atrophic  cirrhosis,  except  that  the  bands  of  newly  formed 
connective  tissue  are  much  heavier.  Characteristic  gummata 
may  be  present  also,  or  they  may  occur  unassociated  with 
connective-tissue  hyperplasia ;  they  appear  as  yellowish  or 
grayish,  firm  rounded  masses,  with  necrotic,  cheesy  centres, 
varying  in  size  from  a  pea  to  that  of  a  hen's  egg. 

Tubercular  lesions  of  the  liver  are  rarely  primary.  Diffuse 
miliary  tubercles  frequently  occur,  however,  in  the  course  of 
general  miliary  tuberculosis ;  in  some  instances  there  are  a 
few  large  foci  only.  A  diffuse  interstitial  connective-tissue 
hyperplasia  is  sometimes  associated  with  the  miliary  tubercles. 


TUMORS. 

Primary  connective-tissue  tumors  do  not  often  occur  in  the 
liver ;  angiomata  more  frequently  than  any  other.  Melanotic 
sarcoma  has  been  observed,  the  black  nodules  of  the  neoplasm 
scattered  through  the  organ,  varying  in  size  from  a  millet- 
seed  to  that  of  a  man's  fist;  much  more  frequently,  how- 
ever, the  tumor  is  secondary  to  melanotic  sarcoma  of  the  eye. 

Primary  epithelial  tumors  of  the  liver  are  also  rare. 

Primary  carcinoma  is  exceedingly  infrequent  as  compared 
with  the  secondary.  It  occurs  either  as  a  large  mass,  gener- 
allv  in  the  right  lobe,  with  secondary  nodules  throughout  the 
organ  ;  or  it  may  occur  as  a  diffuse  infiltration,  which  resem- 
bles atrophic  cirrhosis  of  the  liver  by  reason  of  the  nodular 
appearance  of  the  surface,  and  the  anastomosing  bands  of 
fibrous  tissue  noted  on  section.  But  in  the  islets  between 


400    DISEASES  OF  THE  OASTRO-1NTESTINAL  TRACT. 

them,  however,  there  is  seen  under  the  microscope  the  atypical 
structure  characteristic  of  the  neoplasm,  and  not  liver-tissue. 
Secondary  carcinoma  of  the  liver  is  quite  common,  occurring 
generally  in  the  form  of  rounded  and  umbilicated,  pinkish 
nodules,  varying  in  size  from  a  pea  to  that  of  an  apple,  and 
often  so  numerous  as  to  produce  an  enormous  enlargement 
of  the  organ.  The  liver- cells  surrounding  such  a  nodule 
are  greatly  flattened  and  atrophied.  Microscopically,  their 
structure  usually  recalls  that  of  the  primary  tumor. 

Echinococcus  cyst  is  the  most  important  parasitic  disease  of 
the  liver,  and  is  produced  by  the  larvaB  of  the  tsenia  echino- 
coccus.  There  may  be  one  or  more  cysts,  varying  in  size  up 
to  that  of  a  man's  head.  They  consist  of  a  connective-tissue 
capsule,  inside  of  which  is  the  parasitic  cyst-wall  proper,  from 
which  originate  smaller  vesicles — brood- capsules — and  the 
heads  of  the  immature  tapeworms.  As  long  as  the  parasite  is 
alive  the  cyst  contains  a  clear  non-albuminous  fluid,  in  which 
are  found  scolices,  the  size  of  a  millet- seed,  and  characteristic 
booklets. 

THE  BILE-DUCTS  AND  GALL-BLADDER. 

Inflammation  of  the  bile-ducts  is  generally  secondary  to  an 
inflammation  affecting  the  mucous  membrane  of  the  duodenum. 
It  may  also  be  produced  by  the  presence  of  a  gall-stone  or  an 
intestinal  parasite  which  has  crept  into  the  common  duct. 
The  result  is  an  obstruction  to  the  outflow  of  bile,  and  conse- 
quent absorption  of  bile-pigment,  giving  rise  to  the  condition 
known  as  obstructive  jaundice.  (A  non-obstructive  jaundice 
may  arise  from  increased  haemolysis  in  various  severe  infec- 
tious diseases — as  yellow  fever.) 

Inflammation  of  the  gall-bladder  is  quite  common,  and  has  a 
tendency  to  end  in  suppuration.  It  may  result  from  extension 
of  an  inflammation  from  the  bile-ducts,  or  be  due  to  the 
presence  of  gall-stones  or  retained  bile. 

Stenosis  of  the  bile-ducts  may  arise  from  the  pressure  ex- 
ternally of  an  aneurism,  a  tumor,  or  an  inflammatory  proc- 
ess around  the  duct.  Congenital  atresia  sometimes  occurs. 

Primary  carcinoma  of  the  gall-bladder  is  occasionally  met ; 
the  irritation  produced  by  the  presence  of  gall-stones  is  looked 
upon  as  a  possible  cause. 


THE  PERITONEUM.  401 

THE  PANCREAS. 

Atrophy  of  the  pancreas  is  not  infrequently  found  in  connec- 
tion with  diabetes  mellitus. 

Inflammation  of  the  pancreas  is  a  rare  condition.  Citrhosis 
is  generally  secondary  to  an  inflammatory  process  in  some 
adjacent  tissue ;  occasionally  it  is  seemingly  due  to  alcohol 
and  syphilis. 

Carcinoma  is  the  most  important  tumor  found  in  the  pan- 
creas. It  is  generally  situated  at  the  head  of  the  gland,  though 
the  whole  organ  may  be  in\7olved. 


THE  PERITONEUM. 

Inflammation  of  the  peritoneum,  or  peritonitis,  but  rarely 
occurs  as  a  primary  affection,  as  compared  to  the  frequency  of 
this  condition  in  the  other  large  serous  sacs,  the  pleural  and 
pericardial ;  nearly  always  it  is  secondary.  It  may  be  acute 
or  chronic ;  circumscribed  or  diffuse.  So-called  idiopathic  cases 
occur  at  times  in  which  there  is  no  demonstrable  cause.  In  a 
great  majority  of  instances  bacteria  play  a  most  important 
part  in  exciting  the  inflammatory  process.  They  may  gain 
direct  access  to  the  peritoneum  from  the  blood  in  septicaemia, 
pyaemia,  and  other  infectious  diseases.  Much  more  frequently, 
however,  there  is  a  local  septic  inflammation  of  some  organ 
which  the  peritoneum  covers — as  of  the  uterus  and  its  appen- 
dages, and  of  the  appendix  vermiformis.  The  bacillus  coli 
communis  has  frequently  been  found  in  cases  associated  with 
affections  of  the  intestinal  tract.  Micro  organisms  met  with 
in  other  instances  are  the  streptococcus  and  staphylococcus 
pyogenes,  diplococcus  pneumonia?,  and  gonococcus. 

When  the  infection  takes  place  gradually  and  the  organisms 
are  in  small  numbers,  the  inflammatory  process  may  be  local- 
ized— as  in  connection  with  appendicitis  and  affections  of  the 
pelvic  viscera.  The  entire  peritoneum  may  subsequently 
become  involved,  as  the  result  of  extension  of  the  inflamma- 
tion ;  in  other  cases  it  is  immediately  involved  by  the  intro- 
duction of  a  large  amount  of  infective  material — as 
perforation  of  the  stomach,  or  intestine, 
abscess  into  the  peritoneal  cavity. 

26— Hist. 


\\\\\i  i//"/// 


402    DISEASES  OF  THE  G ASTRO-INTESTINAL   TRACT. 

Chronic  peritonitis  is  characterized  by  thickening  of  the 
peritoneum,  and  the  formation  of  adhesions  between  opposed 
inflamed  serous  surfaces,  as  in  pleurisy. 

Tuberculosis,  primarily  affecting  the  peritoneum,  is  rare. 
The  most  frequent  sources  of  infection  secondarily  are  tuber- 
cular affections  of  the  mesenteric  and  retroperitoneal  lymph- 
atic glands,  of  the  vertebrae,  and  of  the  pelvic  organs  in  the 
female ;  miliary  tubercles  may  occur  in  general  miliary  tuber- 
culosis. 


CHAPTER    VII. 
DISEASES  OF  THE  URINARY  ORGANS. 

THE  KIDNEYS. 
PASSIVE  HYPER.EMIA. 

Passive  hyperaemia  occurs  in  conjunction  with  valvular  disease 
of  the  heart,  and  diseases  of  the  lungs,  which  seriously  impede 
the  circulation — as  fibroid  phthisis  and  severe  emphysema. 

The  kidneys  are  generally  enlarged  in  the  earlier  stages, 
are  firm  and  elastic ;  the  capsule,  which  is  not  adherent,  may 
readily  be  removed,  exposing  a  smooth  surface.  On  section, 
the  cortex  is  found  to  be  congested  and  swollen ;  the  Mal- 
pighian  bodies  may  be  enlarged  and  stand  out  prominently ; 
the  pyramids  are  deeply  congested,  and  have  a  striated  ap- 
pearance, produced  by  dilatation  of  their  bloodvessels. 

At  a  later  stage,  there  may  be  a  very  considerable  hyper- 
plasia  of  interstitial  connective  tissue,  and  the  organ  conse- 
quently more  or  less  decreased  in  size  and  dense — cyanotic 
induration. 

Microscopically,  the  prominent  features  are  the  dilatation 
and  overfilling  of  the  bloodvessels ;  atrophy  of  the  epithelium 
of  the  tubules,  and  a  marked  increase  in  the  amount  of  inter- 
stitial connective  tissue.  Quite  often  there  are  small  extrava- 
sations of  blood  within  the  capsule  of  the  Malpighian  bodies. 

BRIGHT'S  DISEASE 

To  bilateral  inflammations  of  the  kidneys,  in  which  the 
irritant  has  gained  access  through  the  blood,  the  generic  term 
Bright's  disease  is  applied,  after  the  clinician  who  first  ex- 
plored this  important  field  of  pathology,  and  called  attention 
to  the  relation  of  certain  structural  changes  in  these  organs — 
the  inflammatory  nature  of  which  was  later  recognized — to 
albuminuria  and  general  dropsy. 

403 


404  DISEASES  OF  THE   URINARY  ORGANS. 

There  is  nothing  distinctive  of  inflammatory  processes  in 
the  kidneys.  As  in  other  organs,  though  inflammation  affect- 
ing either  the  parenchyma  or  interstitial  connective  tissue 
alone  does  not  occur,  the  changes  may  be  so  much  more  con- 
spicuous in  one  or  the  other  as  to  suggest  the  term  parenchy- 
matous  or  interstitial  inflammation. 

In  acute  inflammation  produced  by  intense  irritants,  the 
glomeruli  and  epithelium  of  the  secreting  tubules  are  mainly 
affected ;  while  in  other  instances  in  which  the  irritant  is  less 
intense  and  acts  over  a  prolonged  period,  the  inflammatory 
changes  predominate  in  the  interstitial  connective  tissue. 

Casts. 

Casts  of  the  uriniferous  tubules  have  been  objects  of  very 
considerable  interest  in  connection  with  these  pathological 

FIG.  186. 


a,  epithelial  casts ;  6,  opaque  granular  casts  (from  a  case  of  acute  Bright's  disease ; 

Roberts). 

changes  since  1842,  when  attention  was  first  directed  to  them 
by  Henle.     They  are  found  in  the  urine,  and  in  the  urinif- 


CASTS. 


405 


erous  tubules  at  the  site  of  their  formation,  in  nearly  all 
inflammations  of  the  kidneys,  and  are  but  rarely  present  in 
normal  urine. 

The  method  of  their  formation  is  not  perfectly  understood 
— some  probably  by  a  species  of  secretion  from  the  tubular 
epithelium,  and  others  by  coagulation  of  serous  exudations 
into  the  tubules. 

In  size  they  vary  according  to  the  part  of  the  kidney  in 
which  they  are  formed,  measuring  from  0.01  to  0.05  milli- 

FIG.  187. 


Granular  casts  (Musser). 


metre  in  diameter,  and  one-tenth  to  a  millimetre  and  more 
in  length.  Several  varieties  are  distinguished. 

Hyaline  casts  are  homogeneous,  transparent,  and  colorless. 
They  are  found  in  the  urine  from  simply  congested  kidneys, 
and  in  transient  albuminuria ;  often,  moreover,  in  chronic 
parenchymatous  and  interstitial  nephritis. 

Granular  casts  are  composed  of  a  granular  material  re- 
sulting from  the  breaking  down  of  the  epithelial  cells  of  the 
tubules.  They  are  found  especially  in  the  urine  from  chronic- 
ally inflamed  kidneys. 


406  DISEASES  OF  THE   URINARY  ORGANS. 

FIG.  188. 


Fatty  casts  from  a  case  of  chronic  parenchymatous  nephritis  (Musser). 
FIG.  189. 


Hyaline  casts  from  a  case  of  acute  nephritis:    1,  plain  hyaline  cast-  2  eranular 
deposits  (hyaline  casts;;  3,  cellular  deposit  (blood  and  epithelium)  (MufsS 

Cellular  casts  occur  when  epithelial  cells,  or  red  and  white 
blood-corpuscles  cling  to  either  of  the  above  varieties. 


ACUTE  PARENCHYMA  TO  US  NEPHRITIS. 


407 


Waxy  casts  have  a  peculiar  glistening  appearance,  which 
distinguishes  them  from  the  hyaline  variety.     The  last  two 
varieties  occur   in   both   acute   and 
chronic  nephritis  (Figs.  186-190).  FIG.  190. 

ACUTE     PARENCHYMATOUS 
NEPHRITIS. 

Acute  parenchymatous  nephritis 
may  be  a  primary  affection,  occur- 
ring often  without  discoverable  cause ; 
or  secondary,  as  a  rather  frequent 
complication  of  scarlet  fever,  diph- 
theria, and  other  acute  infectious 
diseases,  and  of  pregnancy. 

Clinically,  the  condition  is  charac- 
terized by  acute  onset,  scanty,  albu- 
minous, and  often  bloody  urine, 
dropsy,  and  uremia ;  the  most 
prominent  features  are  headache, 
coma,  and  possibly  convulsions,  due 
to  retention  in  the  blood  of  noxious 
substances,  normally  eliminated  by 
the  kidneys. 

Anatomically,  the  appearance  of 
the  kidney  varies  considerably,  ac- 
cording to  the  duration  and  intensity 
of  the  affection. 

Macroscopically,  in  some  instances  of  acute  parenchymatous 
nephritis,  especially  where  the  inflammatory  process  is  limited 
to  the  glvmeruli — glomerulo-nephritis — further  than  a  slight 
hyperaemia  and  swelling  of  the  cortex,  there  may  be  but 
little  evidence  of  the  changes  which  have  taken  place.  Gen- 
erally, however,  the  organ  is  enlarged,  often  to  twice  its  natural 
size,  flabby  and  friable ;  its  capsule  is  tense,  gaping  widely  on 
being  incised,  and  is  easily  detached,  exposing  a  perfectly 
smooth  surface.  In  the  early  stages  the  organ  may  be  deeply 
congested ;  but  later  it  is  often  pale— in  proportion  to  the 
swelling  and  degenerative  changes  in  the  tubular  epithelium, 
and  the  inflammatory  cellular  and  serous  exudations  which 
express  the  blood  from  the  interlobular  vessels. 


Different  forms  of  waxy  casts 
(v.  Jaksch).  • 


408 


DISEASES  OF  THE   URINARY  ORGANS. 


On  section,  the  swollen  and  rounded  appearance  of  the 
kidney  is  seen  to  be  due  mainly  to  a  marked  increase  in  the 
thickness  of  the  cortex.  The  cortex  may  be  intensely  hyper- 


FIG.  191. 


Parenchymatous  nephritis,  a,  cross-section  of  a  convoluted  tubule  of  the  kidney, 
the  lining  epithelium  of  which  is  the  seat  of  albuminoid  degeneration.  The 
cells  are  swollen  and  their  bodies  filled  with  abnormally  coarse  granules.  The 
cells  to  the  left  are  so  far  disintegrated  that  the  nuclei  have  lost  most  of  their 
chromatin.  Such  cells  cannot  recover.  The  cells  to  the  right  are  less  pro- 
foundly altered  and  their  nuclei  retain  sufficient  chromatin  to  stain  slightly. 
These  cells  might,  perhaps,  recover.  Other  convoluted  tubules  similarly 
affected  are  represented  in  oblique  section,  b,  tubule  with  low,  unaffected 
epithelium,  the  nuclei  of  which  stain  deeply  ;  c,  round-cell  infiltration  of  the 
interstitial  tissue  in  the  neighborhood  of  a  Malpighian  body,  the  edge  of  which 
is  just  above  the  line  c.  Section  stained  with  hsematoxylin  and  eosin. 

semic,  with  here  and  there  small  punctiform  hemorrhages,  the 
distended  glomeruli  standing  out  prominently  as  dark  red 
points ;  or  mottled  in  appearance  by  yellow  patches  of  fatty 


ACUTE  PARENCEYMATOUS  NEPHRITIS.  409 

degeneration  ;  or  of  a  uniform  gray  color  in  advanced  stages, 
when  the  leukocytic  infiltration  has  been  excessive — contrast- 
ing strongly  with  the  pyramidal  portion,  which  is  generally 
deeply  congested. 

Microscopically,  also,  the  appearances  presented  in  acute 
parenchymatous  nephritis  differ  greatly  both  in  the  extent 
and  character  of  the  lesion.  In  some  instances  the  changes 
are  almost  entirely  confined  to  the  tubular  epithelium ; 
resembling  rather  an  acute  degeneration  than  an  inflammation. 
At  other  times  there  is  a  diffuse  inflammatory  infiltration,  in 
addition  to  more  or  less  marked  changes  in  the  tubular  epi- 
thelium (Fig.  191)  ;  in  still  other  cases,  to  which  the  term 
glomerulo-nephritis  has  been  applied,  the  inflammatory  changes 
begin  in  and  are  most  marked  around  the  glomeruli,  though 
sooner  or  later  becoming  more  general. 

Just  what  the  essential  differences  are,  in  the  character  of 
the  exciting  cause,  which  are  factors  in  producing  the  varied 
lesions  noted  above,  is  not  kno\vn ;  though  it  might  be  argued 
that,  when  the  poisonous  substance  or  irritant  is  being  elimi- 
nated by  the  epithelial  cells  of  the  secreting  tubules,  the 
changes  may  be  most  marked  there ;  but  if  of  such  a  character 
as  to  be  more  readily  eliminated  with  the  watery  constituents 
of  the  blood  by  wray  of  the  glomeruli,  the  primary  inflamma- 
tory changes  may  be  excited  at  that  point. 

The  changes  in  the  uriniferous  tubules,  most  marked  in  the 
convoluted  portions  in  the  cortex,  consist  of  a  granular  and 
fatty  degeneration  of  the  epithelial  cells,  some  of  which 
become  desquamated  and  distend  the  tubules  ;  at  the  same  time 
the  epithelial  cells  in  places  may  show  proliferative  changes. 
The  epithelium  of  the  glomeruli  may  undergo  similar  degen- 
erative and  proliferative  changes,  and  the  whole  tuft  become 
enlarged  from  engorgement  of  its  bloodvessels.  Migrated 
leukocytes,  and  small  masses  of  extravasated  red  blood -cor- 
puscles, are  often  seen  in  and  around  the  tubules  and  glomeruli. 
To  this  class  of  cases,  in  which  the  parenchymatous  changes 
are  the  most  marked  feature,  the  term  catarrhal  or  desqua- 
mative  nephritis  has  been  applied. 

As  has  been  noted,  in  some  cases,  especially  those  occurring 
in  the  course  of  scarlet  fever,  the  inflammatory  changes  begin 
in  the  Malpighian  bodies — glomerulo-nephritis.  The  glomeruli 


410  DISEASES  OF  THE   URINARY  ORGANS. 

are  swollen  and  infiltrated  with  leukocytes,  and  their  capillary 
bloodvessels  engorged.  Bowman's  capsule  is  thickened ;  its 
cells  swollen,  degenerated,  and  desquamated.  The  interlobular 
arteries  are  more  prominent  than  normal,  and  are  surrounded  by 
migrated  leukocytes.  The  leukocytic  migration  may  be  slight 
or  excessive — occurring  in  foci  or  as  a  diffuse  infiltration  of 
the  cortex.  In  some  cases,  even  at  an  early  date,  there  is  noted 
a  beginning  organization  of  these  migrated  and  proliferating 
cells  into  more  or  less  highly  developed  connective  tissue. 

CHRONIC  NEPHRITIS. 

Chronic  nephritis  may  follow  an  acute  attack,  but  in  the 
great  majority  of  cases  it  arises  insidiously  as  an  independent 
affection.  Clinically  and  anatomically,  two  varieties  of 
chronic  nephritis  are  recognized  :  one  in  which  the  changes 
are  most  marked  in  the  parenchyma  of  the  organ,  and  asso- 
ciated clinically  with  general  dropsy  and  the  passage  of  small 
quantities  of  urine  of  low  specific  gravity,  loaded  with  albu- 
min and  casts — chronic  parenchymatous  nephritis;  and  the 
other,  in  which  the  increase  in  connective  tissue  is  the  most 
marked  feature  anatomically,  and  characterized  clinically  by 
the  absence  of  dropsy,  and  passage  of  large  amounts  of  pale 
urine  containing  comparatively  small  quantities  of  albumin 
and  but  few  casts — chronic  interstitial  nephritis.  These  two 
varieties  may  be  different  stages  of  one  affection,  but,  on  the 
contrary,  many  cases  of  chronic  parenchymatous  nephritis 
never  go  on  to  cirrhosis ;  and  often,  in  other  instances,  the 
connective-tissue  hyperplasia  is  the  most  prominent  feature 
from  the  earliest  stages  of  the  inflammatory  process. 

In  chronic  parenchymatous  nephritis  the  kidney  is  generally 
enlarged,  usually  to  a  greater  extent  even  than  in  acute  nephri- 
tis. The  capsule  is  readily  removed,  exposing  a  smooth  sur- 
face, except,  at  a  somewhat  later  stage,  for  slight  irregularities 
here  and  there,  where  bits  of  the  parenchyma  have  become  ad- 
herent to  the  capsule  and  caused  small  lacerations  on  tearing  it 
away.  The  surface  is  mottled  and  anaemic,  its  pale  appear- 
ance earning  for  it  the  term  large  white  kidney,  though  this 
term  is  applied  to  amyloid  degeneration,  and  other  conditions 
not  included  under  the  head  of  chronic  parenchymatous 
nephritis.  In  consistency  the  organ  is  doughy. 


- 


CHRONIC  INTERSTITIAL  NEPHRITIS.  411 

On  section,  the  cortex  is  found  to  be  two  or  three  times 
its  normal  thickness,  its  mottled  appearance  being  due  to 
patches  of  fatty  degeneration  in  the  tubular  epithelium. 

The  microscopical  lesions  are  the  same  as  in  acute  parenchy- 
matous  nephritis,  only  more  marked.  The  most  prominent 
feature  is  the  degenerative  changes  in  the  epithelium  of  the 
convoluted  tubules ;  the  epithelial  cells  are  swollen,  granular, 
and  many  are  in  an  advanced  stage  of  fatty  degeneration, 
finally  breaking  down  completely,  and  filling  the  lumen  of  the 
tubule  with  a  granular  and  fatty  debris,  the  lining  epithelium 
being  entirely  destroyed.  Within  the  tubules  may  be  also 
hyaline,  granular,  and  fatty  casts.  There  is  generally  some 
increase  in  the  intertubular  connective  tissue.  The  changes 
in  the  glomeruli  are  equally  marked,  increased  thickness  of 
Bowman's  capsule  and  of  the  connective  tissue  between  the 
capillaries  tending  to  convert  them  into  atrophied  fibrous 
bodies. 

In  chronic  interstitial  nephritis  the  kidney  is  usually  greatly 
reduced  in  size — to  less  than  two  ounces  in  extreme  cases — and 
is  remarkably  tough  in  consistency  ;  its  surface  is  of  a  reddish- 
gray  tint,  and  uneven  from  the  presence  of  small  nodules  or 
granulations,  fairly  regular  in  size — about  that  of  a  millet- 
seed.  The  capsule  is  thickened,  opaque,  and  firmly  adherent. 

On  section ,  the  most  noticeable  feature  is  the  marked  atrophy 
of  the  cortex,  appearing  as  a  narrow  rim  but  a  few  millimetres 
in  thickness.  The  pyramids  are  also  reduced  in  size,  the 
atrophy  of  the  intervening  glandular  tissue  giving  them  the 
appearance  of  being  closely  packed  together. 

Microscopically,  the  prominent  features  are  the  atrophy  of 
the  glomeruli  and  uriniferous  tubules,  the  tubular  epithelium 
having  undergone  granular  and  fatty  degeneration  ;  and  great 
increase  in  the  connective-tissue  stroma.  The  majority  of 
glomeruli  have  become  dense  and  fibrous  nodules,  but  one- 
half  their  normal  size.  Here  and  there  may  be  well-preserved 
tubules  and  glomeruli.  Occasionally  tubules  are  met  which 
seem  to  have  undergone  a  sort  of  complementary  dilatation, 
as  the  result  of  obliteration  of  tubules  in  other  areas,  becom- 
ing so  exaggerated  in  some  instances  as  to  form  cysts,  large 
enough  to  be  seen  with  the  naked  eye.  Sometimes  these 
cysts  occur  in  rows,  suggesting  their  origin  from  a  single 


412  DISEASES  OF  THE   URINARY  ORGANS. 

tubule  ;  they  may  also  result  from  the  dilatation  of  Bowman's 
capsules,  and  are  often  filled  with  a  colloid  material.  Hya- 
line and  granular  casts  may  be  found  within  the  tubules.  At 
an  early  stage  of  the  inflammatory  process  the  interstitial 
tissue  may  be  quite  cellular,  but  the  longer  the  duration  of  the 
affection  the  more  fibrous  and  the  greater  the  increase  in  the 
stroma ;  from  its  contraction  results  the  granular  appearance 
of  the  surface.  The  walls  of  the  bloodvessels  are  almost 
invariably  thickened  by  an  obliterating  endarteritis 

Associated  with  these  lesions  in  chronic  interstitial  nephritis 
are  nearly  always  a  general  arterio-sclerosis  and  a  hypertro- 
phied  heart. 

DEGENERATIONS. 

Parenchymatous  degeneration,  or  cloudy  swelling  of  the  kid- 
neys, occurs  in  the  course  of  diphtheria,  scarlet  fever,  cholera, 
and  other  infectious  diseases  ;  and  in  poisoning  from  phospho- 
rus, arsenic,  and  mercury.  There  is  no  sharp  line  of  demarca- 
tion between  this  condition  and  acute  parenchymatous  nephri- 
tis, in  which  it  is  liable  to  terminate,  the  changes  varying  with 
the  virulence  of  the  poison.  The  kidney  is  enlarged,  rounded, 
and  soft  in  consistency.  On  section,  the  cortex  is  thicker  than 
normal,  and  pale  or  yellowish  in  appearance. 

Microscopically,  the  principal  changes  are  noted  in  the 
tubules  of  the  cortex.  The  tubular  epithelium  is  granular 
and  swollen ;  the  lumen  of  the  tubule  almost  entirely  oblit- 
erated, often  appearing  as  little  more  than  a  stellate  fissure. 
The  cell  outline  is  indistinct  and  its  nucleus  obscured. 

Fatty  degeneration  very  frequently  follows  cloudy  swelling ; 
it  often  occurs  also  in  the  course  of  long-continued  wasting 
diseases,  as  cancer,  tuberculosis,  diabetes,  and  pernicious 
anemia.  The  kidney  is  pale  and  extremely  flabby,  and 
often  smaller  than  normal  ;  on  section  the  cortex  is  found  to 
be  of  normal  thickness,  and  of  a  diffuse  yellowish  or  mottled, 
and  greasy  appearance. 

Microscopically,  the  convoluted  tubules  are  especially  af- 
fected ;  the  cells  are  swollen,  and  near  their  bases  are  droplets 
of  fat  of  various  size. 

Amyloid  degeneration  of  the  kidneys  occurs  in  tuberculosis. 


KIDNEYS—THE  SPECIFIC  GRANULOMATA.         413 

syphilis  and  other  cachexias ;  and  is  associated  with  similar 
changes  in  the  liver,  spleen,  and  abdominal  lymphatic  glands. 
It  is  generally  accompanied  by  albumin uria,  and  in  advanced 
stages  by  general  dropsy. 

At  an  early  stage  the  kidney  may  appear  perfectly  normal 
to  the  naked  eye.  Later,  however,  it  is  enlarged,  often  to 
twice  its  normal  size,  pale,  anaemic,  and  very  firm  and  tough. 
The  capsule  can  be  readily  removed,  exposing  a  surface 
smooth,  polished,  and  glistening.  On  section,  the  cortex  is 
thickened  and  has  a  peculiar  transparent,  homogeneous,  bacony 
appearance. 

Microscopically,  the  changes  are  found  to  begin  in  the  walls 
of  the  bloodvessels  as  in  other  organs,  and  hence  are  most 
readily  recognized  at  an  early  stage  in  the  Malpighian  bodies, 
which  appear,  unstained,  as  prominent,  transparent  or  trans- 
lucent, polished  clumps.  The  rose  color  imparted  to  the 
amyloid  material  by  the  use  of  methyl  violet  as  a  stain,  gives 
the  capillaries  of  the  tufts  the  appearance  of  being  injected. 
Later  the  changes  are  noted  in  the  afferent  and  efferent  vessels 
of  the  tufts,  and  arterise  recta?.  Not  infrequently  the  base- 
ment-membrane of  the  uriniferous  tubules  may  be  similarly 
affected — the  lining  epithelium  being  in  various  stages  of 
granular  and  fatty  degeneration.  This  degenerative  change 
is  often  associated  with  parenchymatous  and  interstitial  ne- 
phritis. 

THE  SPECIFIC  GRANULOMATA. 

Syphilis  in  its  early  stages  may  give  rise  to  a  nephritis 
similar  to  that  produced  by  other  infectious  diseases.  In  its 
later  stages  it  is  a  very  frequent  cause  of  amyloid  degenera- 
tion, and  may  also  produce  a  chronic  interstitial  nephritis. 
Syphilitic  gummata  of  the  kidneys  are  very  rare. 

Tuberculosis  occurs  as  a  part  of  an  acute  miliary  or  chronic 
general  tuberculosis,  though  cases  are  seen  in  which  the  disease 
starts  primarily  in  the  kidneys ;  infection  may  take  place 
also  along  the  ureters,  secondarily  to  tuberculosis  of  the  tes- 
ticles, seminal  vesicles,  and  bladder.  The  disease  is  generally 
more  marked  in  one  kidney  than  in  the  other,  or  may  be 
entirely  confined  to  one.  In  primary  tuberculosis  of  the 
kidneys,  at  an  early  stage,  the  tubercular  foci — small  yellow 


414  DISEASES  OF  THE   URINARY  ORGANS. 

caseous  nodules — may  be  confined  to  the  bases  of  the  pyra- 
mids. Discharge  of  the  necrotic  tissue  often  occurs  into  the 
pelvis  of-  the  kidney,  which  is  generally  also  involved — a 
tubercular  pyelo-nephritis.  At  a  later  stage  the  whole  organ 
is  sometimes  converted  into  a  large  sac,  with  caseous  and  ul- 
cerating walls. 

TUMORS. 

Fibromata  are  not  infrequently  found  in  the  kidney  in  the 
form  of  small,  firm,  white  nodules  about  the  size  of  a  millet- 
seed,  though  sometimes  much  larger. 

Lipomata  are  rare,  but  the  fatty  external  capsules  of  the 
kidney  may  be  so  greatly  increased  in  thickness  as  to  form 
practically  a  fatty  tumor  (Fig.  1 1 9). 

Simple  adenoma  has  been  met  with  in  the  kidney,  but  is 
very  rare.  Small  tumors  sometimes  occur,  which  are  formed 
of  a  displaced  remnant  of  the  suprarenal  capsule,  and  histologi- 
cally  resemble  that  gland. 

Leiomyomata  occasionally  occur  in  the  kidney,  and  are 
generally  situated  near  the  apices  of  the  papillae.  A  rare 
tumor,  which  is  usually  congenital,  is  the  rhabdomyosarcoma, 
histologically  found  to  be  composed  of  round  and  spindle- 
cells  mixed  with  striated  muscle-cells. 

Primary  sarcoma  of  the  kidney  is  more  frequent  than 
primary  carcinoma.  Microscopically,  it  varies  considerably 
in  size  and  appearance.  Microscopically,  the  varieties  most 
frequently  met  are  the  round  and  spindle-celled,  the  myxo- 
sarcoma,  and  myosarcoma. 

Primary  carcinoma  of  the  kidney  is  rare.  It  generally  be- 
gins in  the  cortex  as  an  adeno-carcinoma. 

Cysts  occur  frequently  in  the  course  of  chronic  interstitial 
nephritis,  and  even  in  the  otherwise  normal  kidney,  as  the 
result  of  obliteration  and  dilatation  of  the  uriniferous  tubules 
and  Bowman's  capsule,  and  may  attain  sometimes  a  very  con- 
siderable size.  They  may  be  so  numerous  as  to  cause  sur- 
prise that  the  kidney  should  have  been  able  to  perform  its 
functions  at  all.  Congenitally,  both  kidneys  may  be  trans- 
formed into  masses  of  innumerable  cysts  of  varying  size, 
these  organs  being  so  greatly  enlarged  in  some  cases  as  even 


PELVIS  OF  THE  KIDNEY.  415 

to  interfere  with  parturition.     Dermoid  cysts  are  also  found  ; 
echinococcic  cysts  are  of  occasional  occurrence. 

PELVIS  OF  THE  KIDNEY. 

In  inflammation  of  the  pelvis  of  the  kidney — pyelitis — and 
the  associated  lesions  in  the  kidney  itself,  infection  takes  place 
most  frequently  by  way  of  the  ureter,  in  connection  with 
urethral  stricture,  enlarged  prostate,  vesical  calculus,  and 
cystitis.  Though  pyelitis  may  occasionally  occur  in  the  course 
of  infectious  diseases  and  in  non-infectious  cases,  for  example, 
as  the  result  of  the  mechanical  irritation  produced  by  the  pres- 
ence of  calculi,  calculous  pyelitis ;  yet  in  the  majority  of 
cases  it  is  a  septic  or  suppurative  inflammation  produced  by 
micro-organisms.  Sooner  or  later  there  generally  follows  a 
suppurative  inflammation  of  the  kidney  itself — pyelo-nephritis. 

FIG.  192. 


Hydronephrosis  with  granular  atrophy  of  the  kidney.    The  other  kidney  showed  a 
marked  compensatory  hypertrophy  (Virchow). 

In  pyelo-nephritis  the  kidney  is  swollen,  soft,  and  friable, 
its  surface  dotted  with  small  yellow  elevations  which  contain 
pus.  In  size  and  number  these  abscesses  may  vary  greatly. 
They  may  be  few  and  confined  mainly  to  the  cortex,  or  the 
whole  kidney  may  be  fairly  riddled  with  larger  confluent  ab- 
scesses, communicating  with  the  pelvis  of  the  kidney,  the 
whole  organ  in  some  instances  being  converted  into  a  large 
pus-sac— pyo-nephrosi*.  When  obstruction  of  the  ureter  causes 


416  DISEASES  OF  THE   URINARY  ORGANS. 

dilatation  of  the  pelvis  and  calices  of  the  kidney,  hydroneph- 
rosis  is  the  descriptive  term  (Fig.  192). 

Calculi  not  infrequently  occur  in  the  pelvis  of  the  kidney, 
sometimes  attaining  quite  large  dimensions;  the  term  renal 
gravel  is  applied  to  the  smallest  gritty  particles.  During 
their  formation  the  calculi  often  become  more  or  less  accu- 
rately moulded  to  the  shape  of  the  pelvis  and  the  calices. 
They  may  be  composed  of  uric  acid,  oxalate  of  lime,  and 
phosphates,  and  rarely  of  cystin  and  xanthin.  The  results 
of  their  presence  may  be  very  serious.  The  smallest  particles 
may  pass  through  the  ureter  from  time  to  time  and  give  rise 
to  attacks  of  excruciating  pain— renal  colic;  larger  ones,  by 
obstructing  the  ureter  and  the  outflow  of  urine,  may  cause 
hydronephrosis.  The  continued  irritation  produced  by  a 
large  calculus  results  generally  in  a  pyelitis,  and  in  some  cases 
seems  to  be  the  exciting  cause  of  cancer. 

URINARY  BLADDER. 

Fissure  of  the  bladder — a  congenital  malformation — is 
rather  common,  occurring  as  the  result  of  a  failure  of  the 
visceral  arches  to  coalesce  in  front.  The  absence  of  the 
anterior  wall  of  the  abdomen  and  bladder  exposes  to  view, 
protruding  and  filling  the  cleft,  the  inflamed  mucous  mem- 
brane of  the  posterior  wall  of  the  bladder  which  has  been 
pushed  forward  by  the  abdominal  viscera — exstrophy.  The 
extent  of  such  a  fissure  varies  greatly.  It  may  involve  the 
pubic  bones,  and  in  the  female,  the  vagina,  clitoris,  and  urethra; 
or  the  bladder  may  be  perfectly  formed  and  the  cleft  confined, 
in  the  male,  to  the  urethra,  constituting  an  epispadms. 

Hypertrophy  of  the  muscle- walls  of  the  bladder  results 
from  some  obstruction  either  of  the  neck  of  the  bladder  or  of 
the  urethra — as  by  enlargement  of  the  middle  lobe  of  the 
prostate  or  a  urethral  stricture. 

The  mucous  membrane  of  the  bladder  is  raised  into  trabec- 
ulse  by  the  bundles  of  hypertrophied,  interlacing  muscle- 
fibres,  giving  rise  to  an  appearance  somewhat  similar  to  the 
inner  surface  of  the  ventricle  of  the  heart. 

Inflammation   of  the  bladder — cystitis — may   be    acute   or 


URINARY  BLADDER— TUMORS.  417 

chronic,  and  varies  considerably  in  its  severity.  The  inflam- 
matory process  may  extend  from  the  urethra  in  gonorrhoea ;  or 
result  from  the  presence  of  vesical  calculus ;  or  occur  in  the 
course  of  acute  infectious  diseases.  The  introduction  of 
septic  matter  during  catheterization  is  of  common  occurrence ; 
and  the  decomposition  of  urine  consequent  upon  the  retention 
of  urine  in  urethral  stricture  or  hypertrophied  prostate  is  also 
a  frequent  cause. 

The  mucous  membrane  in  acute  cases  may  be  greatly  swollen, 
and  congested,  and  present  numerous  punctate  hemorrhages 
and,  at  times,  superficial  sloughs  ;  its  surface  is  covered  with 
a  muco-purulent  exudate,  and  in  some  cases  a  pseudo-mem- 
brane. 

In  chronic  cases  the  mucous  membrane  is  greatly  thickened, 
and  is  often  the  seat  of  extensive  ulceration  ;  if  there  be  some 
obstruction  to  the  outflow  of  urine,  the  hypertrophied  trabec- 
ulae  of  muscle-fibres  may  give  the  surface  a  ribbed  appear- 
ance. 

In  other  cases,  as  the  result  of  the  organization  and  subse- 
quent contraction  of  the  inflammatory  infiltration  of  its  walls, 
the  bladder  is  often  much  diminished  in  size.  Incrustations 
of  phosphates  deposited  from  the  alkaline  urine  may  cover 
the  surface  of  the  mucous  membrane. 

The  thick,  tenacious,  gelatinous  material  often  present  in 
the  urine,  in  addition  to  large  quantities  of  migrated  leuko- 
cytes, is  not  due  to  the  presence  of  mucin,  but  is  the  result  of 
the  action  of  the  alkaline  urinary  salts  on  the  purulent  exu- 
date. Infection  is  liable  to  extend  along  the  ureters  to  the 
kidneys. 

Tuberculosis  of  the  bladder  may  occur  in  phthisis,  but  is 
much  more  frequently  secondary  to  tuberculosis  of  the  kidney, 
uterus,  prostate,  epididymis,  or  seminal  vesicles. 

The  lesion  generally  presents  as  a  single  large,  or  numerous 
small  ulcers,  most  abundant  at  the  base  of  the  bladder  and 
around  the  orifices  of  the  ureters. 

Tumors  :  Papillomata,  varing  in  size  from  a  pea  to  that  of 
a  pigeon's  egg,  and  often  having  a  cauliflower-like  appear- 
ance, are  of  rather  frequent  occurrence.  They  are  quite 
vascular  and  bleed  readily.  Carcinoma  is  nearly  always 

27— Hist. 


418  DISEASES  OF  THE   URINARY  ORGANS. 

secondary  ;  the  bladder  is  generally  involved  as  the  result 
of  the  extension  of  the  new  growth  from  the  uterus,  vagina, 
or  rectum,  or  rarely  by  metastasis. 

Calculi  are  frequently  found  in  the  bladder,  varying  greatly 
in  size  and  number.  In  some  cases  there  is  a  single  calculus 
four  or  five  inches  in  diameter ;  in  others,  small  gravel-like 
particles. 

The  appearance  of  the  larger  stones  varies  according  to 
their  composition.  The  uric-acid  calculus  is  generally  round 
and  hard,  its  surface  smooth,  and  from  a  yellow  to  a  red 
color.  Mixed  or  triple-phosphate  calculi  are  also  frequent. 
They  are  white,  soft,  and  friable,  with  roughened  surfaces;  or 
occur  as  incrustations  on  the  mucous  surface  of  the  bladder- 
walls.  Caldum-oxalate  or  mulberry  calculi  are  brownish  in 
color,  hard,  and  rounded,  with  irregular  nodular  surfaces. 

THE  URETHRA. 

Inflammation  of  the  urethra,  which  is  in  most  instances  due 
to  the  gonococcus  of  Neisser,  is  a  frequent  and  especially 
serious  disease,  in  its  consequences,  in  the  male.  In  the  great 
majority  of  cases  the  inflammatory  process  involves  the  entire 
extent  of  the  urethra,  though  it  may  be  confined  to  that  por- 
tion anterior  to  the  cut-off-muscle — anterior  urethritis.  The 
gonococci  rapidly  penetrate  between  the  epithelial  cells  beyond 
the  reach  of  antiseptics  and  astringents. 

The  mucous  membrane  is  intensely  congested  and  swollen, 
and  from  it  comes  a  thick,  purulent  exudate. 

If  the  posterior  urethra  is  involved,  the  gonococci  are  very 
apt  to  invade  the  vas  deferens,  and  excite  an  acute  inflamma- 
tion of  the  epididymis ;  the  prostate  gland  may  be  likewise 
involved ;  the  bladder,  however,  is  but  rarely  affected. 

The  inguinal  lymphatic  glands  are  frequently  enlarged,  the 
inflammatory  process  sometimes  terminating  in  suppuration. 

Rarer  complications  of  gonorrhoeal  urethritis  are  arthritis 
and  inflammations  of  the  pericardium  and  endocardium,  and 
even  at  times  of  the  pleura  and  the  spinal  meninges. 

Chronic  urethritis  not  infrequently  follows  the  acute.  Gono- 
cocci have  been  found  as  long  as  six  years  after  an  original 


URETHRA— TUMORS.  419 

infection  in  the  purulent  discharge  from  the  urethra.  Even 
after  the  disappearance  of  these  organisms,  lesions — post- 
gonococci — remain,  which  may  give  rise  to  serious  conse- 
quences. Chronic  posterior  urethritis  is  often  responsible  for 
functional  derangements  of  the  nervous  system — sexual  neuras- 
thenia. In  this  chronic  stage  the  inflammation  is  no  longer 
diffuse,  but  circumscribed.  The  lesions  consist  of  localized 
areas  of  submucous  infiltration  and  erosions,  or  even  definite 
ulcerations  of  the  mucous  membrane ;  at  times  some  patches 
of  granulation-tissue  are  noted. 

Strictures  often  result  at  the  site  of  these  lesions  from  the 
formation  of  cicatricial  tissue.  As  they  gradually  encroach 
upon  the  lumen  of  the  canal  and  impede  the  outflow  of  urine, 
the  bladder-walls  become  hypertrophied ;  but  later  this  organ 
is  dilated,  as  likewise  may  be  the  ureters  and  pelvis  of  the 
kidneys. 

Tumors  :  Carcinoma  of  the  urethra  may  result  from  exten- 
sion of  the  new  growth  from  adjacent  organs,  as  the  vulva, 
vagina,  and  glans  penis  ;  it  is  rarely  primary,  taking  its  origin 
from  Cowper's  gland. 

Sarcoma  of  the  urethra  does  occur,  but  is  very  rare. 


CHAPTER   VIII. 

DISEASES  OF  THE  NERVOUS  SYSTEM. 
THE  MENINGES. 

Inflammation  may  involve  both  the  cerebral  and  spinal 
meninges,  or  either  separately.  The  dura  alone  may  be  affected 
— pachymeningitis ;  the  pia  and  arachnoid  are  usually  affected 
together — leptomeningitis,  or  simply  meningitis. 

In  the  cord,  however,  all  three  membranes  are  commonly 
involved  at  the  same  time,  together  with  the  periphery  of  the 
white  matter  of  the  cord  itself,  with  which  the  meninges  are 
intimately  connected. 

Pachymeningitis :  In  the  brain  inflammation  of  the  outer 
layer  of  the  dura — pachymeningitis  externa — is  generally 
secondary  to  disease  or  injury  of  the  bones  of  the  skull,  of 
which  it  forms  the  periosteum.  The  inflammatory  process  is 
usually  suppurative  and  confined  to  limited  areas,  though  it 
may  extend  to  the  other  membranes  and  the  brain. 

A  suppurative  pachymeningitis  interna  is  generally  asso- 
ciated with  a  leptomeningitis  or  a  pachymeningitis  externa. 

In  chronic  pachymeningitis  there  is  a  diffuse  or  circum- 
scribed thickening  of  the  membrane,  which  is  abnormally 
adherent  to  the  cranium  and  to  the  arachnoid,  and  not  infre- 
quently an  ossification  of  the  outer  layers  of  the  membrane 
takes  place. 

Hemorrhagic  pachymeningitis,  or  hsematoma  of  the  dura, 
occurs  especially  in  chronic  alcoholics  and  the  insane.  The 
condition  is  looked  upon  as  a  hemorrhagic  inflammation  of 
the  dura.  There  first  forms  a  highly  vascular  subdural 
pseudo-membrane,  extending  over  the  greater  part  of  one  or 
both  hemispheres,  the  hsematoma  resulting  secondarily  from 
rupture  of  its  vessels.  This  pseudo-membrane  presents  the 
appearance,  microscopically,  of  granulation-tissue,  and  contains 
many  thin-walled  bloodvessels. 

420 


LEPTOMEN1NGIT1S. 


421 


Leptomeningitis :  In  leptomeningitis  the  inflammatory  proc- 
ess nearly  always  involves  the  arachnoid  and  pia  of  both  brain 
and  cord*.  The  condition  may  occur  as  an  epidemic  cerebro- 
spinal  meningitis;  or  in  the  course  of  smallpox,  scarlet  fever, 


FIG.  193. 


Hydrocephalus  interims ;  dilated  ventricles  (U.  S.  A.  Museum,  No.  8233). 

pneumonia,  septicaemia,  and  other  infectious  diseases.  The 
pneumococcus  is  the  organism  most  frequently  found  asso- 
ciated with  the  disease,  having  been  met  with  in  60  per  cent, 
of  all  cases. 


422 


DISEASES  OF  THE  NERVOUS  SYSTEM. 


In  some  cases  the  macroscopieal  changes  are  not  marked, 
consisting  simply  of  congestion,  loss  of  normal  lustre,  and 
slight  oedema.  In  more  severe  cases  the  exudate,  which  may 
be  serous,  sero-purulent,  or  purulent,  becomes  more  marked, 
and  even  distends  the  subarachnoidal  space,  the  cerebral  con- 
volutions being  flattened  and  the  brain  compressed  to  such 
an  extent  as  to  give  rise  to  coma.  The  ventricles  may  be  like- 
wise distended  (Fig.  193).  In  some  cases  the  exudate  pre- 

FIG.  194. 


Fibrinous  leptomeningitis.  a,  cerebral  cortex  ;  6,  serum,  with  detritus,  separating 
the  brain  from  the  pia  mater  ;  c,  bloodvessel  of  the  pia  mater,  the  walls  of  whicn 
are  infiltrated  with  emigrating  leukocytes  ;  d,  fibrinous  exudate  ;  e,  smaller  ves- 
sel of  the  pia  (Dunham). 

sents  as  an  extensive,  thick,  opaque,  fibrinous  deposit  on  the 
under  surface  of  the  arachnoid.  In  other  instances  a  green- 
ish-yellow, purulent  exudate  may  cover  the  surface  of  the 
brain  to  such  an  extent  as  to  conceal  almost  entirely  the  con- 
volutions of  the  cortex  (Figs.  194  and  195).  The  inflamma- 


TUBERCULAR  MENINGITIS. 


423 


tory  process  may  extend  to  the  substance  of  the  brain,  vary- 
ing from  slight  oedema  of  the  cortex  to  abscess-formation. 

Tubercular  inflammation  of  the  meninges  is  more  common 
in  children  than  in  adults,  and  is  usually  part  of  a  general 
miliary  tuberculosis  or  secondary  to  tuberculosis  of  other 


FIG.  195. 


-  a 


6  — 


Serous  leptomeningitis.  a,  cedematous  fibrous  tissue  of  the  pia  mater,  the  fibrous 
elements  of  the  tissue  being  separated  by  the  serous  exudate ;  6,  group  of  leuko- 
cytes, probably  held  together  in  part  by  fibrin ;  c,  granular  fibrin  and  detritus  :  6 
and  c  and  other  similar  masses,  lie  in  the  serum,  which  occupies  the  whole 
field  between  the  visible  elements  (Dunham). 

regions  of  the  body,  most  commonly  the  lungs.  The  miliary 
tubercles  are  most  numerous  in  the  pia  at  the  base  of  the 
brain.  The  meninges  are  congested,  and  may  be  the  seat  of 
exudations  similar  to  those  occurring  in  simple  meningitis. 
The  ventricles  of  the  brain  are  distended  with  a  serous  exu- 
date and  their  walls  studded  with  miliary  tubercles.  The 


424  DISEASES  OF  THE  NERVOUS  SYSTEM. 

cortex  of  the  brain  is  congested  and  the  convolutions  flattened 
by  pressure  from  within. 

At  times  large  caseous  nodules  are  found  in  the  pia  mater 
and  brain-tissue. 

Syphilitic  inflammation  of  the  meninges  is  generally  circum- 
scribed. The  gummata  which  form  involve  the  pia  and 
the  cerebral  cortex,  or  they  may  extend  outward  and  involve 
the  dura. 

Tumors :  Endothelioma  is  probably  the  tumor  most  fre- 
quently met  in  the  meninges.  Lipomata,  fibromata,  and 
myxomata  are  of  rare  occurrence. 


THE  BRAIN. 

THROMBOSIS  AND  EMBOLISM. 

The  results  of  thrombosis  and  embolism  in  the  brain  may 
be  most  serious,  producing  death,  or  more  or  less  extensive 
paralyses. 

Emboli  are  brought  most  frequently  from  fibrinous  vegeta- 
tion on  the  cardiac  valves,  or  from  cardiac  or  aneurysmal 
thrombi.  They  generally  lodge  in  the  left  middle  cerebral 
artery. 

Thrombosis  is  most  frequent  in  the  basilar  artery,  but  may 
occur  anywhere,  as  the  result  of  the  presence  of  an  embolus, 
or  some  local  inflammatory  or  degenerative  alteration  of  the 
vessel-wall  at  the  site  of  its  formation. 

In  either  case  the  result  of  this  obstruction  of  the  blood- 
supply  is  a  rapid  necrotic  softening  of  the  area  affected — 
encephalomalacia.  The  nerve-cells  degenerate  and  lose  their 
axis-cylinder  processes;  the  myelin-sheaths  of  the  nerve- 
fibres  undergo  fatty  degeneration  ;  and  later  the  neuroglia- 
fibres  a  similar  change.  A  more  or  less  pigmented  scar  is 
finally  formed,  composed  mainly  of  neuroglia-tissue.  In  the 
case  of  an  infectious  embolus,  an  abscess  may  form.  These 
areas  of  softening  are  usually  red  from  the  extravasation  of 
blood,  as  in  infarcts  in  other  organs ;  at  a  later  stage  when 
most  of  the  pigment  has  been  absorbed,  or  when  little  or  no 
blood  has  been  extravasated,  they  are  yellow  or  white. 


CEREBRAL  HEMORRHAGE.  425 

ANEMIA. 

Anaemia  of  the  brain  may  depend  on  general  anaemia,  or  in 
acute  cases  be  due  to  severe  hemorrhage.  The  condition  is 
supposed  to  occur  during  sleep,  in  fainting  spells  and  hysteri- 
cal crises. 

The  gray  and  white  matter  on  section  appear  much  whiter 
than  normal,  and  the  small  puncta  vasculosa  are  almost  en- 
tirely absent.  A  local  anaemia  may  result  from  partial 
obstruction  of  the  blood-supply  by  a  thrombus  or  embolus, 
or  the  external  pressure  of  a  tumor. 

HYPEKffiMIA. 

An  acute  hyperaemia  of  the  brain  may  be  produced  by  ex- 
cessive activity  of  the  heart's  action,  and  accompanies  exces- 
sive brain-work,  sunstroke,  acute  delirium,  and  some  infectious 
diseases,  as  cholera  and  hydrophobia. 

A  passive  hyperaemia  may  result  from  valvular  disease  of 
the  heart  and  from  interference  with  the  return  circulation 
through  the  jugular  veins  by  pressure  of  a  tumor,  or  by  dis- 
ease of  the  lungs — as  extensive  pneumonias  and  large  pleuritic 
effusions.  The  brain  is  enlarged,  the  bloodvessels  of  the  pia 
mater  injected  ;  the  gray  matter  may  have  a  diffuse  rosy  tint, 
and  on  section  the  puncta  vasculosa  are  more  conspicuous 
than  normal.  In  passive  hyperaemia,  however,  the  gray 
matter  has  a  slaty  color  and  the  sinuses  and  cortical  veins  are 
widely  distended.  (Edema  of  the  brain  may  result  if  the 
condition  is  long  continued. 

CEREBRAL  HEMORRHAGE. 

The  clinical  term  apoplexy  is  still  used  synonymously  with 
cerebral  hemorrhage,  of  which  it  is  the  most  striking  symptom. 

The  most  important  factors  in  the  production  of  cerebral 
hemorrhage  are  increased  blood-pressure  and  the  degenerative 
changes  occurring  in  the  bloodvessel-walls  with  advancing 
years,  and  in  the  course  of  various  diseases,  notably  syphilis. 
The  resulting  clots  vary  greatly  in  size  ;  they  may  be  as  small 
as  a  pea,  or  almost  entirely  occupy  one  hemisphere.  Usually 
there  is  but  one  clot.  They  occur  most  frequently  in  the 


426          DISEASF:S  OF  THE  NERVOUS  SYSTEM. 

corpora  striata  and  optic  thalami,  and  the  brain-tissue  imme- 
diately surrounding. 

If  there  is  not  a  fatal  termination  of  the  hemorrhage,  in  a 
short  time  the  clot  undergoes  complete  liquefaction,  and,  hav- 
ing been  surrounded  by  a  fibrous-tissue  capsule,  a  sort  of  cyst 
results ;  or  later  there  may  be  simply  a  pigmented  scar  to 
mark  the  site  of  the  hemorrhage. 

Secondary  degeneration  of  the  direct  and  crossed  pyramidal 
tracts  results,  when,  as  is  often  the  case,  the  hemorrhage  has 
occurred  in  the  region  of  the  internal  capsule;  due,  it  is  sup- 
posed, to  the  separation  of  these  motor-nerve  fibres  from  their 
trophic  centres. 

INFLAMMATION. 

Acute  inflammation  of  the  brain — encephalitis — may  occur 
in  the  course  of  various  acute  infectious  diseases,  as  typhoid 
fever,  septicaemia,  and  influenza.  The  condition  is  character- 
ized by  the  formation  of  localized  areas  of  softening,  which  are 
red  or  yellow  in  color,  according  to  the  amount  of  extra vasa ted 
blood  present. 

Microscopically,  in  these  areas,  and  also  in  others  where 
softening  is  not  yet  manifest,  the  bloodvessels  are  dilated, 
engorged  with  blood,  and  surrounded  with  migrated  leuko- 
cytes. The  ganglion-cells  and  nerve-fibres  undergo  a  granular 
and  fatty  degeneration.  In  the  centre  of  the  area  the  neurog- 
lia  undergoes  a  similar  change ;  at  the  periphery,  however, 
may  be  noted  the  formation  of  new  neuroglia  cells  and  fibres. 

Suppurative  inflammation  of  the  brain  is  most  frequently 
associated  with  a  similar  inflammation  of  the  meninges.  The 
condition  may  also  occur  in  the  course  of  pyaemia,  ulcerative 
endocarditis,  and  other  septic  processes;  and  in  influenza,  pneu- 
monia, and  other  infectious  diseases ;  or  it  may  follow  direct 
injury,  or  septic  inflammation  of  the  bones  of  the  skull. 

The  abscess-formations  which  characterize  this  condition 
may  be  quite  small,  or  large  enough  to  contain,  in  one  case, 
as  much  as  four  hundred  cubic  centimetres  of  pus.  In  a  large 
proportion  of  cases  the  abscess  is  solitary  ;  multiple  abscesses 
are  generally  metastatic. 

Chronic  inflammation  of  the  brain  is  characterized,  like 
chronic  inflammation  of  other  organs,  by  an  increase  of  the 


TUBERCULOSIS  OF  THE  BRAIN. 


427 


connective-tissue  elements — the  neuroglia,  cells  and  fibres; 
and  a  partial  or  complete  atrophy  of  the  parenchyma — the 
ganglion-cells  and  nerve-fibres.  The  lesion  may  be  confined 
to  a  lobe.  In  other  cases,  especially  in  drunkards  and  in 
general  paralysis  of  the  insane,  the  greater  part  of  the  brain 


FIG.  196. 


Sarcoma  of  brain  (TJ.  S.  A.  Museum,  No.  7983). 

may  be  involved.  In  still  other  instances  there  are  multiple 
areas  of  sclerosis  irregularly  distributed  throughout  the  brain 
and  cord,  the  grayish  or  grayish-pink  plaques  varying  in  size 
from  that  of  a  pea  to  that  of  an  almond. 

Tuberculosis  of  the  brain — the  most  frequent  "  tumor  "  for- 
mation— is  a  common  lesion,  presenting  usually  as  caseous, 
circumscribed  nodular  masses  the  size  of  an  egg  or  larger. 


428  DISEASES  OF  THE  NERVOUS  SYSTEM. 

The  lesion  exists  most  frequently  in  the  cerebellum  and  is 
more  common  in  the  young  than  later  in  life. 

Syphilis:  Gummata  of  the  brain  nearly  always  originate 
primarily  in  the  meninges.  A  syphilitic  endarteritis  may  also 
produce  diffuse  or  circumscribed  changes  in  the  brain-tissue. 

Tumors  of  the  brain  are  of  especial  importance  by  reason  of 
the  inflammatory  and  degenerative  changes  resulting  from 

FIG.  197. 


Sarcoma  developed  between  the  hemispheres,  posteriorly  (U.  S.  A~TMuseum,  No.  8400). 

their  pressure  on  the  brain- tissue.  The  glioma  is  the  tumor 
most  frequently  met;  it  is  generally  solitary  and  grows  always 
from  the  neuroglia-tissue — never  from  the  pia.  fiarcoma  oc- 
curs next  in  frequency — generally  the  round-celled  variety. 
(Figs.  196  and  197.)  Carcinoma  may  occur  as  a  metastatic 
growth  in  the  brain,  but  never  primarily. 


DEGENERATIONS  OF  THE  CORD. 


429 


THE  CORD. 

HEMORRHAGE. 

Hemorrhage  is  of  much  less  frequent  occurrence  and  much 
less  extensive — the  clot  generally  not  more  than  one  centi- 
metre in  diameter — than  in  the  brain.  The  condition  is 
generally  the  result  of  trauma,  though  it  may  occur  sponta- 
neously. When  the  central  canal  of  the  cord  is  dilated  and 
filled  with  blood  the  term  hcematomyelia  is  employed. 

DEGENERATIONS. 

FIG.  198.  Secondary  degenerations  occur 

in  the  brain  and  cord  as  the 
result  of  any  lesion  interrupting 
the  course  of  nerve-fibres  in  the 
brain,  cord  itself,  or  posterior 
nerve-roots.  These  changes  are 
supposed  to  be  due  to  the  re- 
moval of  normal  trophic  influ- 
ences arising  in  the  ganglion- 
cells  from  which  the  nerve-fibres 
are  cut  off.  The  result  is  the 
destruction  of  the  medullary 
sheaths  of  the  fibres,  to  which  is 
due  their  opaque  white  appear- 
ance. Tracts  in  the  cord  so 

FIG.  199. 


Descending  degeneration  in  the  pyr- 
amidal tract  following  hemorrhage 
into  the  internal  capsule.  The  di- 
rect tract  is  marked,  and  is  repre- 
sented at  a  lower  level  than  it  is 
usually  seen  (F.  W.  Mott). 


The  ascending  tracts  of  degeneration  in 
the  cervical  enlargement  after  experi- 
mental hemisection  of  the  spinal  cord 
in  the  mid-dorsal  region.  The  section 
shows  well-marked  degeneration  of 
Goll's  column,  of  the  direct  cerebellar 
tract,  and  of  the  antero-lateral  tracts  on 
the  same  side  as  the  lesion  (F.  W.  Mott). 


430 


DISEASES  OF  THE  NERVOUS  SYSTEM 


affected  have  a  gray  or  yellowish-gray  color  in  consequence, 
and  hence  the  condition  is  often  spoken  of  as  gray  degenera- 


FIG.  200. 


FIG.  201. 


PRIMARY  DEGENERATIONS  OF  THE  CORD.         431 
FIG.  202. 


Sections  of  the  spinal  cord  at  the  cervical  (Fig.  200),  dorsal  (Fig.  201),  lumbar  (Fig. 
202),  levels  showing  ascending  degeneration,  unilateral,  in  the  posterior  column 
after  a  gumma  involving  the  second  and  third  lumbar  nerve-roots.  The  relative 
extent  of  the  degenerated  fibres  at  the  different  levels  is  shown  in  the  sections 
(Starr). 

tion.  In  addition,  microscopically,  there  is  noted  a  reduction 
in  the  number  of  nerve-fibres,  and  sometimes  a  new  formation 
of  connective  tissue. 

A  descending  degeneration  affecting  the  pyramidal  tracts 
occurs  as  the  result  of  hemorrhage  or  other  lesion  in  the  brain, 
interrupting  the  course  of  the  motor  fibres  (Fig.  198). 

Ascending  degenerations  occur  after  destruction  of  the  cord 
or  posterior  spinal  nerve-roots,  or  from  any  cause  interrupting 
the  course  of  the  ascending  sensory  fibres  of  the  cord,  involv- 
ing the  column  of  Goll,  direct  cerebellar,  and  antero-lateral 
tracts  (Figs.  199-202). 

Primary  Degenerations. 

Sclerosis  of  the  posterior  columns,  or  locomotor  ataxia,  is  the 
most  important  form  of  primary  degeneration  of  the  cord. 
Though  the  macroscopic  and  microscopic  changes  are  marked, 
and  have  been  carefully  studied,  the  true  nature  of  these 


432 


DISEASES  OF  THE  NERVOUS  SYSTEM. 
FIG.  203. 


Diagrammatic  representation  of  the  supply  of  the  groups  of  anterior-horn  cells  by  the 
radicular  branches  of  the  anterior  median  arteries,  showing  one  group  of  cells 
completely  destroyed  by  occlusion  of  one  of  these  small  vessels,  and  thus  ex- 
plaining why  in  poliomyelitis  there  is  usually  permanent  loss  of  movement  in 
some  one  or  more  muscles  (F.  W.  Mott). 


FIG.  204. 


The  lesion  in  the  posterior  columns  at  the  first  dorsal  region  in  a  case  of  locomotor 

ataxia  (Starr). 


PRIMARY  DEGENERATIONS  OF  THE  CORD.        433 

alterations  is  not  fully  understood.  By  a  majority  of  pathol- 
ogists,  however,  they  are  regarded  as  secondary  to  disease  of 
the  posterior  roots  or  their  ganglion-cells.  By  many,  syphilis 
is  regarded  as  the  most  frequent  cause  of  this  condition. 

Macroscopically,  in  well-advanced  cases  the  cord  usually 
appears  atrophied,  especially  in  the  region  of  the  posterior 
white  columns,  which  are  narrow  and  sunken,  and  gray  or 
grayish-yellow  in  color  (Figs.  203  and  204).  On  trans- 

FIG.  205. 


€&. J 


Section  of  spinal  cord  about  the  eighth  dorsal  segment  (from  a  case  of  locomotor 
ataxia).  There  is  sclerosis  of  the  postero-external  column  and  atrophy  of  the 
fine  plexus  of  nerve-fibrils  surrounding  the  cells  of  Clarke's  column  ;  moreover, 
a  band  of  sclerosis  is  seen  entering  the  column  instead  of  the  bundle  of  nerve- 
fibres.  The  cells  themselves  are  atrophied  and  their  processes  destroyed.  This 
case  was  of  interest  because,  in  connection  with  these  lesions,  the  patient  had 
well-marked  visceral  symptoms— gastric  crises,  bladder  troubles,  and  laryngeal 
crisis— in  addition  to  the  ordinary  ataxic  symptoms.  X  100  diameters  (F.  W. 
Mott). 

verse  section  these  changes  are  found  to  be  most  marked  in 
the  lumbar  or  dorsal  regions — the  central  gray  matter  is  not 
generally  affected. 

28— Hist. 


434  DISEASES  OF  THE  NERVOUS  SYSTEM. 

Microscopically,  the  characteristic  features  are  found  to  be 
an  increase  of  the  neuroglia-tissue  and  destruction  of  the 
myelin-sheaths,  and  later  of  the  axis-cylinder — whether  the 
nervous  tissue  or  the  neuroglia-tissue  is  primarily  affected  is 
not  known  (Fig.  205).  Similar  changes  may  occur  in  the 
cranial  nerves,  especially  in  the  optic,  and  in  the  spinal  nerves. 

The  prominent  clinical  feature — inco-ordination — is  due  to 
the  interference  with  the  centripetal,  nerve-fibres,  especially 
those  coming  from  the  muscles.  This  explains  also  the  early 
loss  of  muscle-reflexes.  Actual  loss  of  muscle-power  indicates 
implication  of  the  motor  tracts  in  the  lateral  columns  ;  and 

FIG.  206. 


Photo-micrograph  of  a  section  of  the  cervical  spinal  cord  (from  a  case  of  amyo- 
trophic  lateral  sclerosis).  Degeneration  of  the  crossed  pyramidal  and  direct 
tracts  and  the  antero-lateral  ground-fibres.  The  direct  cerebellar  tracts,  the 
antero-lateral  ascending  tracts,  and  especially  the  posterior  columns,  are  unaf- 
fected. There  was  almost  complete  absence  of  cells  and  fine  nerve-fibre  retic- 
ulum  in  the  anterior  horns;  this  is  observable  by  the  difference  in  color  as 
compared  with  the  posterior  horns  (F.  W.  Mott). 

localized  atrophies,  which  may  aifect  certain  groups  of  muscles, 
if  not  due  to  such  paralysis,  results  from  the  extension  of  the 
disease  to  the  anterior  cornua. 

Friedreich's  disease,  or  hereditary  ataxia,  occurs  at  an  early 
age,  generally  in  several  members  of  the  same  family.  Ana- 
tomically, the  characteristic  features  are  degenerative  changes 
in  the  posterior  and  lateral  columns,  involving  the  pyramidal 
and  direct  cerebellar  tracts. 

Spontaneous  lateral  sclerosis  (Erb's  spastic  paraplegia)  is  a 


PROGRESSIVE  SPINAL  MUSCULAR  ATROPHY.     435 

primary  degeneration  affecting  the  lateral  columns,  especially 
the  pyramidal  tracts.  The  changes  usually  begin  in  the 
lumbar  cord,  and  are  bilateral.  The  chief  clinical  character- 
istics are  paralysis,  muscular  spasms,  and  exaggerated  muscle- 
reflexes  ;  the  first  being  of  course  readily  accounted  for,  and 
the  two  latter,  in  part  at  least,  may  be  referred  to  the  absence 
of  the  control  exercised  by  the  higher  centres  upon  those  in 
the  cord,  and  transmitted  normally  through  the  tracts  now 
degenerated. 

In  some  cases,  to  which  the  term  amyotrophic  lateral 
sclerosis  has  been  applied,  the  anterior  cornua  of  gray  matter 
are  also  involved,  adding  muscular  atrophy  to  the  symptoms 
already  present  (Figs.  206  and  207). 

FIG.  207. 


The  same  as  previous  figure,  except  that  the  section  is  of  the  seventh  to  eight  dorsal 
segments.  The  pyramidal  tracts  are  sclerosed,and  there  is  considerable  degen- 
eration in  the  intermedio-lateral  tract  (F.  W.  Mott). 

Progressive  spinal  muscular  atrophy  (chronic  anterior  polio- 
myelitis) is  characterized  by  a  gradual  atrophy  of  the  large 
ganglion-cells  of  the  anterior  cornua  ;  and  clinically  by  pro- 
gressive atrophy  and  consequent  paralysis  of  the  muscular 
system — commonly  being  first  manifest  in  the  hand.  Though 
the  degenerative  changes  affect  mainly  the  ganglion-cells  of 
the  anterior  cornua.,  the  motor  fibres  arising  from  them,  and 


436  DISEASES  OF  THE  NEEVOVS  SYSTEM. 

probably,  in  most  cases,  both  the  direct  and  crossed  pyramidal 
tracts  are  involved.  In  some  instances  the  pyramidal  tracts 
in  parts  of  their  course  may  be  affected  before  the  anterior 
cornua,  which  could  account  for  the  spasmodic  rigidity  in 
localized  muscle-groups  sometimes  seen.  Generally,  however, 
there  is  no  clinical  evidence  of  the  involvement  of  the  pyram- 
idal tracts. 


INFLAMMATION. 

Under  the  term  myelitis — inflammation  of  the  cord — is  in- 
cluded, according  to  different  authors,  a  great  variety  of 
affections.  By  many  the  primary  degenerations  just  briefly 
described  are  included  under  this  heading.  To  those  cases  in 
which  the  changes  are  limited  in  their  longitudinal  extent  the 
term  transverse  myelitis  has  been  applied,  in  contradistinction 
to  others  in  which  a  considerable  length  of  the  cord  is  involved  : 
to  which  the  term  poliomyelitis  (TTO^OC — gray)  has  been  ap- 
plied when  the  changes  are  confined  to  the  gray  matter  alone  ; 
or  leukomyelitis  (huxb$ — white),  when  confined  to  the  white 
matter. 

Acute  transverse  myelitis,  resulting  in  softening  of  the  cord 
and  characterized  clinically  by  paralysis  of  motion  and  sensa- 
tion below  the  site  of  the  lesion,  may  arise  without  assignable 
cause.  It  may  be  due  to  trauma,  exposure  to  cold,  or  excessive 
venery,  and  certain  of  the  acute  infectious  diseases  have  been 
regarded  as  exciting  causes. 

According  to  the  color  of  the  involved  area,  several  stages 
are  described — as  red  and  yellow  softening,  and  gray  degener- 
ation. 

At  the  first  stage  the  tissue  is  pink  from  the  engorgement  of 
the  bloodvessels,  and  minute  hemorrhages  here  and  there. 

Microscopically,  the  bloodvessels  are  dilated  and  surrounded 
by  migrated  leukocytes,  the  neuroglia-tissue  is  swollen  and  its 
cells  sometimes  increased  in  number.  The  ganglion-cells  are 
likewise  swollen,  and  show  a  diminished  staining  capacity, 
vacuolization,  varicosity  of  their  protoplasmic  processes,  and 
dislocation  of  their  nucleus  toward  the  periphery  of  the  cell. 

At  a  later  stage  the  tissue  is  yellow,  pressure-anamia  having 


ACUTE  TRANSVERSE  MYELITIS. 


437 


given  rise  to  fatty  degeneration  of  the  exudate  and  of  the 
myelin-sheaths  of  the  nerve-fibres.  Microscopically,  the 
nerve-fibres  are  found  to  be  swollen  and  granular,  and  the 
myelin-sheaths  filled  with  droplets  of  fat.  Everywhere  are 
numerous  leukocytes,  and  possibly  some  neuroglia-cells  which 
have  taken  up  the  disintegrated  myelin,  and  on  account  of 
their  appearance  have  been  designated  compound  granular  cells. 
The  myelitis  rarely  goes  on  to  suppuration,  though  the 
affected  area  may  undergo  complete  liquefaction  (Fig.  208). 

FIG.  208. 


a,  changes  on  the  eleventh  day  after  section  of 
a  frog's  sciatic  (Gray). 


6,  changes  on  the  fifteenth 
day  after  section  (Gray). 


Usually,  however,  the  fat  is  absorbed,  and,  the  myelin- 
sheaths  having  been  entirely  destroyed,  a  condition  of  gray 
degeneration  or  softening  remains. 


438 


DISEASES  OF  THE  NERVOUS  SYSTEM. 


FIG.  209. 


Chronic  transverse  myelitis  may  follow  an  acute  attack,  the 
chief  characteristic  being  a  marked  increase  in  the  neuroglia- 
tissue  in  addition  to  the  changes  already  noted.  Similar 
changes  may  also  be  produced  by  chronic  compression  of  the 
cord  resulting,  for  instance,  from  the  growth  of  a  tumor  in 
the  meninges  (Fig.  209),  or  the  bony  deformity  produced  by 
Pott's  disease. 

Acute  anterior  poliomyelitis  is  an  acute  inflammation  of  the 
anterior  cornua  of  the  gray  matter  of  the  cord  accompanied 

by  marked  systemic  disturbances. 
On  account  of  its  greater  frequency 
in  childhood,  the  condition  is  known 
clinically  as  "infantile  paralysis," 
though  the  disease  does  occur  in  the 
adult,  and  is  recognized  as  "  acute 
spinal  paralysis."  Nothing  definite 
is  known  as  to  its  course,  though 
by  many  it  is  regarded  as  an  infec- 
tious disease,  having  a  selective 
action  on  the  tissues  which  are 
affected. 

Macroscopically,  characteristic 
alterations,  which  are  most  marked 
in  the  lumbar  and  cervical  enlarge- 
ments, may  be  entirely  absent  at  an 
early  stage  of  the  disease,  though 
the  changes  consecutive  to  the  cessa- 
tion of  the  acute  inflammatory  proc- 
ess are  quite  obvious,  consisting 
of  sclerosis  and  atrophy  of  the 
anterior  gray  coruna  and  the 
ante ro -lateral  white  columns. 

Microscopically,  at  an  early  stage 
the  bloodvessels  of  the  anterior 
cornua  are  dilated  and  surrounded 
by  migrated  leukocytes,  and  there 
have  also  been  noted  swelling  and  granular  degeneration  of 
the  large  ganglion-cells.  At  a  later  stage,  even  within  a  few 
days  of  the  onset  of  the  disease,  the  ganglion-cells  lose  their 


Meningitis   and 
pression 


3   and   beginning 
-myelitis  from  an 


dural  tumor  (Bock). 


rom  an  extra- 


ACUTE  ANTERIOR  POLIOMYELITIS. 
FIG.  210.  FIG.  211. 


439 


Anterior  cornua  from  case  of  poliomyelitis,  showing  atrophy  of  the  ganglion- 
cells.  For  comparison  the  appearance  of  healthy  cornua  is  shown.  The  small 
black  triangles  represent  the  cells  as  they  appear  under  a  low  magnification 
(F.  W.  Mott). 

FIG.  212. 


Spinal  cord  at  sixth  cervical  level,  from  a  case  of  infantile  paralysis.  The  atrophy  of 
the  right  anterior  horn,  the  existence  of  sclerotic  scar-tissue  in  the  horn,  as  well  as 
the  absence  of  groups  of  cells,  are  shown.  The  left  anterior  horn  is  normal  (Starr). 


440  DISEASES  OF  THE  NERVOUS  SYSTEM. 

nuclei  and  protoplasmic  processes,  and  the  cell-body  becomes 
shrunken  and  finally  entirely  disappears.  The  nerve-fibres  of 
the  anterior  roots  show  fatty  degeneration  of  the  myelin-sheaths 
and  fragmentation  of  the  axis-cylinders  (Figs.  210-212). 

FIG.  213. 


Sarcoma  of  the  spinal  cord  (Bock). 


Of  primary  tumors  the  glioma  and  sarcoma  are  the  types 
most  frequently  encountered  (Fig.  213). 


INDEX. 


A. 

Abscess  of  liver,  394 
Acid  stains.  25 
Actinomycosis,  267 

of  lungs,  356 
Adenocarcinoma,  302 
Adenoid  tissue,  52,  85 
Adenoma,  299 

simple,  of  kidney,  414 
Adipose  tissue,  52 
Adrenal  glands,  108 
capillaries  of,  109 
cortex  of,  109 

zona  fasciculata,  109 
glomerulosa,  109 
reticularis,  109 
general  structure  of,  108 
internal  secretion  of,  110 
lymph -passages  of,  109 
medulla  of,  109 
sustentacular    connective    tissue 

of,  108 
Agminate  glands  of  small  intestine, 

131 

Air- vesicles,  149 
Alimentary  system,  1 11 
Allantois,  191 
Alveolar  sarcoma,  297 
Alveoli,  195 
Amnion,  190 

Amoeboid  movement  of  cells,  30 
Amphi-arthrosis,  200 
Amyloid  degeneration,  277,  323,  327 

of  kidney,  412 
Anaemia,  312 
of  brain,  425 
local,  270 

pernicious,  progressive,  313 
primary,  312 
simple,  313 
secondary,  317 


Aneurism,  329 

cylindrical,  329 

fusiform,  329 

sacculated,  329 
Angeioma,  294 

cavernous,  294 

lymphangeiomata,  294 
Angeiosarcomata,  297 
Aphthous  stomatitis,  359 
Apoplexy,  425 
Appendicitis,  385 
Appendix  vermiformis,  133 
Arachnoid,  211 
Areolaf  tissue,  50 
Arteries,  77-79 

terminal,  78 

tunica  adventitia,  78 
intima,  77 
media,  77 

Arterio-sclerosis,  328 
Arteritis,  327 

chronic,  328 
Asiatic  cholera,  386 
Atelectasis,  336 
Atheroma,  328 
Atrophy,  284 

acute  yellow,  of  liver,  393 

of  heart,  318 

progressive  spinal  muscular,  435 
Attraction-sphere,  27 
Axis-cylinder,  207 

processes,  205 
Axon,  207 

B. 

Bacillus  of  Eberth,  386 
Bacteria,  pathogenic,  269 

saprophytic,  269 
Basement  membranes,  52 
Basic  stains,  25 
Bile-ducts,  136  3 

(441) 


442 


INDEX. 


Bile-ducts,  inflammation  of,  400 
-passages,  138 
stenosis  of,  400 
Bladder,  168 
calculi  in,  418 
coats  of,  168 
fibrous,  169 
mucous,  168 
muscular,  169 
fissure  of,  416 
hypertrophy  of,  416 
inflammation  of,  416 
tuberculosis  of,  417 
tumors  of,  417 
Blastoderm,  40 
Blood,  65,  91-103 
circulation  of,  75 
-corpuscles,  91 
red,  92 

alterations  in,  310 
decay  of,  95 

difference  of,  in  vertebrate, 
functions  of,  94 
number  of,  93 
•origin  of,  95 
structure  of,  94 
white,  97 

consistency  of,  97 
number  of,  97 
shape  of,  97 
size  of,  97 
structure  of,  97 
surface  of  97 
diseases  of,  309 
anaemias,  312 
plethora,  309 
oligemia,  309 
glands,  67,  104 
-plasma,  91 
-plates,  103 

alterations  in,  311 
qualitative  changes  in,  309 
Bloodvessels,  dilatation  of,  251 
diseases  of,  327 
degenerations,  327 
arteritis,  327 
phlebitis,  330 
of  kidney,  165 
of  lung,  146 
of  salivary  glands,  120 
of  small  intestines,  132 
of  spleen,  105 


Bloodvessels  of  stomach,  128 

of  thyroid  gland,  107 
Bone,  56-60 
areola>,  58,  59 
primary,  58 
secondary,  59 
calcined,  56 
cancellous,  56 
-cells,  48,  56 
compact,  56 
decalcified,  56 
development  of,  58 
cartilaginous,  58 
membranous,  59 
fibres  of  Sharpey,  57 
lacunae,  57 

Howship's,  60 
marrow,  57 
function,  58 
red,  57 

cells,  57 
yellow,  58 
matrix,  56 
lamellae,  57 
system,  57 

Haversian,  57 
intermediate,  57 
peri-medullary,  57 
peripheral,  57 
perforating  fibres,  58 
tissues,  56 
cancellous,  56 
compact,  56 

Bowman,  membrane  of,  126 
Brain,  diseases  of,  424 
ana?mia,  425 

cerebral  hemorrhage,  425 
embolism,  424 
hyperaemia,  425 
acute,  425 
passive,  425 
inflammations,  426 
acute,  426 
chronic,  426 
suppurative,  426 
syphilis,  428 
thrombosis,  424 
tuberculosis,  427 
tumors,  428 
ventricles  of,  213 
Bright's  disease,  403 
Bronchi,  147 


INDEX. 


443 


Bronchi,  structure  of,  148 
Bronchial  tubes,  diseases  of,  333 
Bronchiectasis,  335 
Bronchitis,  333 

acute,  333 

chronic.  335 

fibrinous,  335 
Bronchopneumonia,  343 
Bronchorrhoea,  335 
Brownian  movements  of  cells,  31 
Brunner,  glands  of,  131 
Budding,  34 
Bursae,  200 

c. 

Cachectic  oedema,  273 
Calcareous  infiltration,  282,  323, 
Calcification,  282 
Calculi  in  bladder,  418 
Canal  of  Petit,  229 
Cancrum  oris,  360 
Capillaries,  80 

stomata,  80 

Capillary  bloodvessels,  263 
Capsule  of  Glisson,  134 
Carcinoma,  301 

of  bladder,  417 

of  brain,  428 

cylindrical-celled,  302 

of  intestines,  392 

of  liver,  primary,  399 
secondary,  400 

of  mouth,  360 

of  pancreas,  401 

primary,  of  gall-bladder,  400 
of  kidney,  414 

simplex,  302 

squamous-celled,  303 

of  stomach,  375 

of  urethra,  419 
Cardiac  dropsy,  272 

hypertrophy,  319 
Carotid  glands,  106 
Cartilage,  52 

-cells.  48 

cellular,  55 

hyaline,  53 

of  larynx,  143 

perichondrium,  54 

white  fibre-,  54 

yellow  elastic,  55 


327 


Casts,  404 
cellular,  406 
granular,  405 
hyaline,  405 
waxy,  407 

Catarrhal  stomatitis,  359 
Cavernous  angeioma,  294 
Cells,  20,  22 
body,  24 

contents  of,  24 
bone-,  48 
cartilage-,  48 
classes  of,  22 

differentiated  or  specialized,  23 
connective  tissue,  23 
epithelial,  23 
muscle,  23 
nerve-,  23 
free-living,  22 
generalized  or   undifferentiated, 

22 

leukocyte,  23 
ova,  23 
single,  23 
independent,  22 
of  Claudius,  240 

connective-tissue,  23 
connective  tissue,  47 
bone-,  48 
cartilage-,  48 
fat-,  48 
flattened,  48 
fusiform,  47 
granular,  48 
irregular,  48 
lamellar,  48 
mast-,  48 
mucous,  47 
neuralgia-,  48 
odontoblasts,  48 
pigmented,  48 
plasma-,  48 
round,  47 
spherical,  47 
stellate,  47 
wandering,  49 
cortical,  119 
cyclosis,  30,  31      - 
definition  of,  22 
of  Deiters,  239 
epithelial,  23 
fat,  48 


444 


INDEX. 


Cells,  forms  of,  28 

disc-shaped,  28 

flattened,  28 

oval,  28 

spherical,  28 
free,  64 
functions  of,  29 

motion,  29 

nutrition,  29 

sensibility,  29 
ganglion,  202 
granules,  25 
gustatory,  119 
of  Hen  sen,  240 
of  Langerbans,  221 
leukocytes,  23 
lymphoid,  64 
mast-,  48 
movements  of,  30 

amoeboid,  30 

Brownian,  31 

ciliary,  31 

contraction,  30 
mucous,  47 
muscle,  23,  60 
nerve-,  23,  202 

of  cord,  215 
neuralgia,  48 
olfactory,  142 
origin  of,  33 
ova,  23 
plasma  of,  48 
processes,  28 
properties  of,  29 
of  Purkinje,  213 
reproduction  of,  modes  of,  33 

budding,  34 

direct  division,  33 

indirect  division,  karyokinesis  or 
mitosis,  34 

segmentation,  34 
single,  23 
size  of,  29 
spaces,  82 
spores,  23 
structure  of,  23 

body,  23 

cell-wall,  24 

centrosome,  23 

intimate,  31 

nucleus,  23 
tactile,  221 


Cells,  vital  properties  of,  29 
wall,  27 

wandering,  49,  64 
Cellular  cartilage,  55 
casts,  406 

exudate,  function  and  fate  of,  254 
fluids,  65 
blood,  65 
lymph,  65 
semen,  65 

Cement  intercellular,  32 
Centrosome,  27 

Cerebellar  cortex,  gray  matter  of,  213 
Cerebellum,  213 

superficial  portion,  213 
Cerebral  cortex,  gray  matter  of,  211 

hemorrhage,  425 
Cerebro-spinal  meningitis,  211 
Cerebrum,  211 

gangl ionic  parts  of,  212 
Chemotaxis,  252 
negative,  102 
positive,  102 
Chlorosis,  312 
Chondroma,  292 
Chorion,  190 
Choroid,  226 
Chrematin,  36 
Chromatin,  26 
Chromophilic  granules,  203 
Chyle,  103 
Cilia,  27 

motion  of,  28 
Ciliary  body,  228 

movements  of  cells,  31 
Circulatory  apparatus,  269 
anaemia,  local,  270 
embolism,  271 
hypersemia,  269 
active,  269 
passive,  270 
ischsemia,  270 
oedema,  272 
thrombosis,  270 
system,  75 
arteries,  77 

tunica  adventltia,  78,  79 
intima,  77,  79 
media,  77,  79 
capillaries,  80 
diseases  of,  318 
arteritis,  327 


INDEX. 


445 


Circulatory  system,  diseases  of,  atro- 
phy, 318 

degenerations,  327 
degenerative  changes,  321 
hypertrophy,  319 
inflammations,  323 
phlebitis,  330 
heart,  75 

vascular  sinuses,  80 
veins,  79 

Circumvallate  papillae  of  tongue,  118 
Cirrhosis  of  liver,  396 
Clitoris,  194 

Cloudy  swelling  degeneration,  281 
Coagulation-necrosis,  275 
Coccygeal  gland,  106 
Cochlea,  236 
Cohnheim,  experiments  of,  248 

fields  of,  61 
Colitis,  acute,  381 
Colloid  degeneration,  280 
Colostrum,  197 
Columnar  epithelium,  44 
Common  ducts,  138 
Conjugation,  38 
Conjunctiva,  224 
Connective  tissue,  47 
cells.     See  Cells, 
changes,  255 
distribution,  47 
extracellular  elements,  47 
of  lung,  145 
varieties  of,  49-60 
Cord,  spinal,  degenerations  of,  429 
ascending,  431 
descending,  431 
primary,  431 
secondary,  429 
hemorrhage  of,  429 
inflammations  of,  436 
tumors  of  440 
Corium,  153 
Cornea,  226 

epithelial  layer  of,  226 
Corpora  cavernosa,  179 

lutea,  185 

Corpus  spongiosum,  180 
Corpuscles,  concentric.  89 
of  Hassall,  89 
of  Krause,  222 
of  Meissner,  222 
of  Pacini,  223 


Corpuscles,  tactile,  221 
Cortical  cells,  119 
Cowper's  glands,  179 
Crenation,  93 
Croupous  stomatitis,  359 
Crura  cerebri,  213 
Crypts  of  tonsil,  122 
Crystalline  lens,  229 
Cutis  vera,  153 
Cylindrical-celled  cancer,  302 
Cystic  ducts,  138 
Cystitis,  416 
Cystosome,  24 
Cysts,  307 

disintegration,  308 

of  kidnev,  414 

retention,  308 
Cytolemma,  27 
Cytoplasm,  2 

D. 

Decidua,  191 

Degenerations,  amyloid,  277,  323,  327, 
412 

cloudy  swelling,  281 

colloid,  280 

fatty,  277,  327,  412 

granular,  281 

hyaline,  281,  323 

of  kidneys,  412 

lardaceous,  277 

mucoid,  280 

parenchymatous,  281,  412 

of  spinal  cord,  429 
ascending,  431 
descending,  431 
primary  431 
secondary,  429 

waxy,  277 

Degenerative  changes,  321 
Dendrites,  205 

functions  of,  206 
Dentinal  fibre,  114 

sheath,  114 

tubules,  114 
Derm  is,  153 
Development,  33-41 

of  embryo,  40 
Diapedesis,  252 
Diath  roses,  200 
1  Differentiation,  40 


446 


INDEX. 


Diphtheria,  361 
Disintegration  cysts,  308 
Ductless  glands,  68,  104 
Ducts,  common,  71 

ejaculatory,  378 

interlobular,  70 

intermediate,  70 

intralobular,  70 
Duodenal  glands  of  small  intestine, 

131 

Duodenitis,  381 
Dura  mater,  211 

E. 

Ear,  233 

external,  234 

middle,  234 
Eberth,  bacillus  of,  386 
Echinococcus  cyst  of  liver,  400 
Ectoplasm,  24 
Ectosarc,  24 
Ejaculatory  ducts,  178 
Elements,  extracellular,  20,  22,  32,  47 

non-cellular,  20,  22 

ultimate,  19,  22 
Embolism,  271 

of  brain,  424 

Embryo,  development  of,  40 
Emphysema,  336 

interstitial,  336 

vascular,  336 
Empyema,  358 
Emulsions,  66 
Encephalitis,  426 
End-bulbs,  222 
Endocarditis,  324 

acute,  324 

chronic,  325 
Endocardium,  75 

valves  of,  75 
Endomysium,  61 
Endoplasm,  24 
Endosarc,  24 

Endothelial  sarcomata,  298 
Endothelioma  of  meninges,  424 
Endothelium,  42,  46 
Enteritis,  380 

Eosinophile  leukocytes,  100 
Epiblast,  40 

tissues  developed  from,  41 
Epidermis,  151 


Epididymis,  176 

canal  of,  176 
Epiglottis,  143 
Epimysium,  61 
Epithelioma,  303 
of  larynx,  333 
primary  of  liver,  399 
Epithelium,  42-4(5 
columnar,  44 
ciliated,  45 
simple,  45 
stratified,  45 
non-ciliated,  44 
simple,  44 
stratified,  44 
function  of,  43 
glandular,  45 
goblet,  45 
location  of,  42 
neuro,  46 
pigmented,  46 
simple,  44 
specialized,  46 
neuro-,  46 
pigmented,  46 
squamous,  simple,  43 

stratified,  43 
structure  of,  42 
transitional,  44 
varieties  of,  43 
Erectile  tissue,  81 
Erythroblasts,  58 
Erythrocytes,  92 
Eustachian  tube,  234 
Exudate,  cellular,  function  and  fate 

of,  254 

serous,  function  of,  255 
Eye,  224 
Eyelids,  233 

F. 

Fallopian  tubes,  186 
Fasciae,  200 
Fat-necrosis,  276 

Fatty  degeneration,  277,  3'22,  327 
of  kidney,  412 

glands,  72 

infiltration,  177 

tissue,  52 

Ferrein,  pyramids  of,  160 
Fertilization  of  ovum,  39 


- 


INDEX. 


447 


Fever,  267 

anatomical  changes,  269 
etiology  of,  268 
significance  of,  269 
Fibres,  32 

development  of,  49 
perforating,  57 
of  Sharpey,  57 
white,  49 
yellow  elastic,  49 
Fibroblasts,  47,  263 
Fibroma,  290 

of  kidney,  414 
Fibrosis,  286,  345 
Filliform  papillae  of  tongue,  118 
Fissure  of  bladder,  416 
Flagella,  27 

motion  of,  28 

Fluids,  body,  64 

cellular,  65 

emulsions,  66 

chyle,  66 

milk,  66 

homogeneous,  65 

Foetal  membrane,  191 

appendages,  190 

allantois,  191 

amnion,  190 

chorion,  190 

decidua,  191 

foetal  membrane,  191 

placenta,  192 

umbilical  cord,  193 

vesicle,  191 
villi,  192 

Foliate  papillae  of  tongue,  119 
Follicles  of  Lieberkiihn,  130 
Fovea  centralis,  233 
Friedreich's  disease,  434 
Fungiform  papillae  of  tongue.  118 

G. 

Gall-bladder,  138 

inflammation  of,  400 

primary  carcinoma  of,  400 
Ganglia,  "216 

of  posterior  roots,  217 

sympathetic,  217 

typical,  217 
Ganglion-cells,  202 
Gangrene,  276 


!  Gangrene  of  lung,  346 
circumscribed,  346 
diffuse,  346 

Gangrenous  stomatitis,  360 
Gastrectasia,  366 
Gastric  ulcers,  372 

dangers  of,  374 
Gastritis,  366 
acute  toxic,  367 
chronic,  368 
glandularis  atrophica,  370 

prolifera,  369 
mucipara,  369 
purulent,  367 
simple  acute,  366 

Gastro-intestinal  tract,  diseases  of,  359 
Gastroptosis,  366 
Gemmation,  34 
Genital  organs,  female,  182 
mammary  glands,  194 
ovary,  182 
oviducts  or   Fallopian    tubes, 

186 

uterus,  187 
vagina,  193 
vulva,  194 
male,  172 

Cowper's  glands,  179 
epididymis,  176 
penis,  179 
prostate  gland,  178 
seminal  vesicles,  177 
testicle,  172 
vas  deferens,  177 
Giant-celled  sarcoma,  297 
Giraldes,  organ  of,  177 
Glanders,  267 

of  lungs,  356 
Glands,  67 

adrenal  or  suprarenal,  108 
agminate,  90 

of  small  intestine,  131 
of  Bartholin,  194 
blood,  67,  104 
of  Brunner,  131 
carotid,  106 
coccygeal,  106 
corpuscles  of  Hassall,  89 
cortex,  89 
Cowper's,  179 
ductless,  104 
functions  of,  104 


448 


INDEX. 


Glands,  duo'denal,  of  small  intestine, 

131 

fatty,  72 
lachrymal,  233 
Luschka's,  106 
lymph oid,  67 

of  small  intestine,  131 
mammary,  194 
medulla,  89 
Meibomian,  233 
mucous,  71 

of  tonsils,  122 
parotid,  120 
prostate,  178 
saccular,  compound,  70 

simple,  70 
salivary,  120 

inflammation  of,  365 
sebaceous,  157 
secretory,  67 
closed,  68 
ductless,  68 
morphology  of,  70 
open,  68 
saccular,  70 
compound,  70 
simple,  70 
tubular,  70 
compound,  70 
simple,  70 
serous,  71 
solitary,  90 
sublingual,  121 
submaxillary,  122 
thy m us,  88 
thyroid,  107 
of  tongue,  117 
tubular,  compound,  70 

simple,  70 
of  Tyson,  180 
uterine,  188 

Glandular  epithelium,  45 
Glioma,  306 

of  brain,  428 
Glisson,  capsule  of,  134 
Goblet  epithelium,  45 
Graafian  follicles,  184 
Granular  casts,  405 
degeneration,  281 
Granulation  tissue,  262 
Granules,  of  cells,  25 
basophile,  25 


Granules,  colorless,  25 
Dobie's,  62 
Ehrlich's  division,  25 
eosinophile,  25 
neutrophile,  25 
oxyphile,  25 
pigmentary,  25 
Granulomata,  infective,  264 
actino  mycosis,  267 
glanders,  267 
leprosy,  267 
rhinoscleroma,  267 
syphilis,  267 
tuberculosis,  264 
Granuloplasm,  24 
Gustatory  cells,  119 

H. 

Hsemaglobin,  amount  of,  311 
Hsemothorax,  356 
Hairs,  154 
bulb,  154 
cortex  of,  155 
cuticle,  155 
follicle,  155 
medulla,  of,  155 
roots,  154 
Healing  by  first  intention,  259 

by  second  intention,  260 
Heart,  75 

and  pericardium,  diseases  of,  318 
atrophy,  318 

degenerative  changes,  321 
hypertrophy,  319 
inflammations,  323 
valves  of,  75 

Hemorrhagic  infarcts  of  lungs,  339 
Henle,  layer  of,  156 
Henle's  loop,  164 

ascending  limb  of,  165 
descending  limb  of,  164 
Hensen,  line  of,  62 
Hepatic  artery,  136 
ducts,  138 
veins,  136 
Hernia,  379 
Histologic  structures,  analysis  of,  19 

of  man,  19 
technique,  20 
Homogeneous  fluids,  65 
Howship's  lacunae,  60 


INDEX. 


449 


Hyaline  cartilage,  53 

casts,  405 

degeneration,  281,  323 

matrix,  32 
Hyaloplasm,  24 
Hydronephrosis,  416 
Hydrothorax,  356 
Hymen,  194 
Hypera?mia,  269 

active,  269 

of  brain,  425 
acute,  425 
passive,  425 

passive,  270,  337 
of  kidneys,  403 
of  liver,  393 
Hypertrophy,  285 

of  bladder,  416 

cardiac,  319 
causes  of,  319 

causes,  285 
Hypoblast,  40 

tissues  developed  from,  41 
Hypoplasia,  284,  285 

of  heart,  318 

I. 

Infarcts,  271 

Infective  granulomata  of  lung,  347 
Infiltration,  calcareous,  282 
and  degenerations,  276 
fatty,  277 
pigmentary,  283 

extrinsic,  284 

intrinsic,  283 
Inflammation,  247 
of  bile-ducts,  400 
of  bladder,  416 
of  brain,  426 

acute,  426 

chronic,  426 

suppurative,  426 
of  cord,  436 
definition  of,  247 
of  gall-bladder,  400 
interstitial,  259 
of  liver,  394 

acute  purulent,  394 

chronic  interstitial,  396 
of  meninges,  420 
of  pancreas,  401 


Inflammation,  parenchyinatous,  259 
of  pelvis  of  kidney,  415 
of  peritoneum,  401 
productive,  259 
purulent,  256 
suppurative,  256 
of  urethra,  418 
variations  in  type  of,  255 
Interlobular  ducts,  70 

septa,  70 

Intermediate  duct,  70 
Interstitial  emphysema,  336 

inflammation,  259 
Intestines,    acquired  deformities  and 

displacements  of,  379 
congenital  deformities  and  displace- 
ments of,  378 
inflammations  of,  380 
acute  colitis,  381 
appendicitis,  385 
duodenitis,  381 
enteritis,  380 
specific,  386 

Asiatic  cholera,  386 
syphilis,  391 
tuberculosis,  390 
typhoid  fever,  386 
large,  132 

muscular  coat  of,  132 
small,  128   . 

agminate  glands  of,  131 
bloodvessels  of,  132. 
duodenal  glands  of,  131 
lymphatic  vessels  of,  132 
lymphoid  glands  of,  131 
mucous  membrane  of,  129 
muscular  coat  of,  131 
muscularis  mucosse,  131 
nerves  of,  132 
subepithelial   connective    tissue, 

130 

submucosa,  131 

serous  or  peritoneal  coat  of,  132 
walls  of,  128 
tumors  of,  392 
Intralobular  capillaries,  137 
ducts,  70 
veins,  137 

Intussusception,  380 
Iris,  228 
Irritants,  256 
Ischsemia,  270 


450 


INDEX. 


K. 

Karyokinesis,  26,  34 
Kidneys,  158 

bloodvessels  of,  165 
cortex  of,  160 
diseases  of,  403 

Bright's  disease,  403 
cysts,  414 
degenerations,  412 
amyloid,  412 
fatty,  412 

parenchymatous,  412 
granulomata,  specific,  413 
syphilis,  413 
tuberculosis,  413 
hypereemia,  passive,  403 
nephritis,  acute  parenchymatous, 

407 

chronic,  410 
interstitial,  411 
parenchymatous,  410 
tumors,  414 

general  structure  of,  158 
medulla  of,  158 
pelvis  of,  1 68 
inflammation  of,  415 
wall  of,  168 
sustentacular  connective  tissue  of, 

160 

uriniferous  tubules  of,  162 
Krause,  membrane  of,  62 
tactile  corpuscles  of,  222 


Lachrymal  canals,  233 

gland,  233 
Lactation,  194 
Langerhans'  bodies,  140 

cells  of,  221 

Lardaceous  degeneration,  277 
Laryngitis,  acute,  332 

chronic,  333 
Larynx,  143 
cartilages  of,  143 

diseases  of,  332 

epithelioma,  333 

laryngitis,  332 

papillomata,  333 

sarcoma,  333 

syphilis,  333 

tuberculosis,  333 


Larynx,  ligaments  of,  143 
mucous  membrane  of,  143 
epithelial  lining,  143 
submucosa,  143 
tunica  propria,  143 
Leiomyoma  of  kidney,  414 
Lei  )inyomata,  305 
Leprosy,  267 

of  lungs,  356 
Leptomeningitis,  421 
Leukaemia,  314 
Leukocyte,  23 

Leukocytes,  alterations  in,  311 
cell-bodies  of,  98 
nuclei  of,  98 
number  of,  97 

origin  and  development  of,  102 
structure  of,  97 
varieties  of,  98 
eosinophile,  100 
large  mononuclear,  99 
polymorphonuclear     or     neutro- 

phile,  100 

small  mononuclear,  99 
transitional,  99 
vital  properties   and   functions  of, 

101 

Leukocythsemia,  314 
Leukocytosis,  311 
Lieberkiihn,  follicles  of,  130 
Ligament,  suspensory,  229 
Ligaments  of  larynx,  143 
Linin,  26 
Lipoma,  291 

of  kidney,  414 
I  Liquefaction-necrosis,  276 
I  Liquor  sanguinis,  91 

seminis.  181 
Liver,  133 
-cells,  136 
diseases  of,  393 

atrophy,  acute  yellow,  393 
hypersemia,  393 
inflammations,  394 
syphilis,  399 
tuberculosis,  399 
tumors,  399 

general  structure  of,  134 
lobules  of,  136 
sustentacular  or  connective  tissue 

134 
Localized  cedemas,  273 


INDEX. 


451 


Locomotor  ataxia,  431 
Lungs,  145 

bloodvessels  of,  146 
connective  tissue  of,  145 
diseases  of,  336 
actinomycosis,  356 
atelectasis,  336 
emphysema,  336 
gangrene,  346 
glanders,  356 
hemorrhagic  infarct,  339 
hypersemia,  passive,  337 
leprosy,  356 
oedema,  338 
pneumonia,  chronic  interstitial, 

345 

lobar,  339 
lobular,  343 
syphilis,  355 
tuberculosis,  347 
tumors,  356 
lymphatics  of,  147 
nerves  of,  147 
pyramidal  lobules  of,  145 
Luschka's  gland,  106 
Lymph,  65,  82,  103 
-cords,  87 
-corpuscles,  103 
follicles,  85 
-sinuses,  89 
medullary,  87 
peripheral,  87 
-spaces,  82 

of  Fontana,  228 
Lymphangeioma,  294 
Lymphatic  glands,  86 
capsule  of,  87 
circulation  through,  88 
cortex  of,  88 
elements  of,  86 
functions  of,  90 
medulla,  88 
origin  of,  83 
vessels  of,  87 
afferent,  87 
efferent,  88 
system,  82 
action  of,  82 
lacteals  of,  84 

morphologic  elements  of,  82 
origin  of,  83 
vessels  of,  82,  84 


Lymphatic  system,  vessels  of,  coats,  84 

valves,  85 
vessels,  84 

of  small  intestine,  132 
of  spleen,  106 
of  stomach,  128 
Lymphatics  of  lung,  147 
of  salivary  glands,  120 
of  thyroid  gland,  108 
Lymphoid  cells,  64 

of  tonsil,  122 
glands,  67 

of  small  intestine,  131 
tissue  of,  52,  85 
cells  of,  85 
diffuse,  85 
functions  of,  90 
meshes,  85 
nodules,  85 

M. 

Macula  lutea,  233 
Malpighi,  pyramids  of,  158 
Malpighian  body,  162 

arrangement  and  function,  163 
corpuscles,  106 
Mammary  glands,  194 
secretion  of,  196 
sustentacular     connective    tissue 

of,  195 

Margination,  250 
Marrow,  function  of,  58 
red,  57 
yellow,  58 
Mast-cells,  48 
Maturation  of  ovule,  38 
Medulla  oblongata,  213 
Medullary  sheath,  208 
Medullated  nerve-fibres,  207 
Meibomian  glands,  233 
Meissner,  tactile  corpuscles  of,  221 
Melanotic  sarcoma,  298 
Membranes,  51 
basement,  52 
of  Bowman,  226 
distant,  51 
of  Krause,  62 
mucous,  72 
epithelium,  72 
muscularia  mucosae,  72 
secretion,  73 


452 


INDEX. 


Membranes,  mucous,  submucosa,  72 

tunica  propria,  72 
of  Nasmyth,  114 
of  Reissner,  237 
serous,  73 

connective  tissue,  73 
endothelium,  73 
parietal,  73 
subserous  tissue,  73 
visceral,  73 

Meninges,  diseases  of,  420 
leptomeningitis,  421 
pachymeningitis,  420 
chronic,  420 
hemorrhagic,  420 
syphilis,  424 
tuberculosis,  423 
tumors,  424 
Mesoblast,  40 
Metakinesis,  37 
Micropyle,  41 

Microscopical  appearances  of  inflamed 
animal  membranes,  248 
first  stage,  248 
second  stage,  249 
third  stage,  250 
Mineral  matters,  32 
Mononuclear  leukocytes,  large,  99 

small,  99 
Mouth,  111 
diseases  of,  359 
stomatitis,  359 
syphilis,  360 
thrush,  360 
tuberculosis,  360 
tumors,  360 

mucous  membrane  of,  111 
of  epithelial  layer,  111 
of  submucosa,  112 
of  tunica  propria,  112 
Mucoid  degeneration,  280 
Mucosa,  72 
Mucous  cells,  47 
glands,  71 

of  tongue,  117 
membranes  72 
of  larynx,  143 
of  mouth,  111 
of  nasal  fossae,  141 
of  oesophagus,  125 
of  pharynx,  124 
of  small  intestine,  129 


Mucous  membranes  of  tongue,  116 
of  trachea,  144 
of  uterus,  187 
Mumps,  365 
Muscle  cells,  60 
cardiac,  62 

involuntary  or  non-striated,  63 
striated  or  striped,  60 
voluntary,  198 

motor  end-plates  of,  320 
Muscular  coat  of  large  intestine,  132 

of  urethra,  170 
structures,  198 
substance  of  tongue,  116 
Myelitis,  acute  transverse,  436 

chronic  transverse,  438 
Myeloid  sarcomata,  297 
Myeloplaxes,  51 
Myocarditis,  323 
Myocardium,  75 
Myoma,  304 

leiomyomata,  305 
rhabdomyomata,  304 
Myomalacia  cordis,  323 
Myxoma,  291 


Nails,  157 

root  of,  157 
Nasal  fossae,  141 

mucous  membrane  of,  141 
olfactory  portion,  142 
respiratory  portion,  142 
passages,  diseases  of,  332 
rhinitis,  332 
syphilis,  332 

Nasmyth,  membrane  of,  114 
Necrosis,  274 
varieties  of,  275 
caseation,  276 
coagulation,  275 
fat,  276 
gangrene,  276 
liquefaction,  276 

Nephritis,  acute  parenchymatous,  407 
chronic,  410 
interstitial,  411 
parenchymatous,  410 
Nerves,  217 

arrangement  of,  217 
Nerve-cells,  202 
of  spinal  cord,  215 


INDEX. 


453 


Nerve-centres,  209 

-fibres,  207 

mednllated,  207 
non-medullated,  208 

filaments  of  salivary  glands,  120 

of  lung,  147 

of  small  intestine,  132 

-terminals,  218 
classes  of,  218 

-tissue,  64 

Nervous  system,  202 
diseases  of,  420 
division  of,  202 
Neuraxons,  205 
Neurilemma,  208 
Neurites,  205 

function  of,  206 
Neuro-epithelium,  46 
Neuroglia,  209 

-cells,  48 

Neurokeratin,  208 
Neuroma,  306 
Neurons,  64,  206 
Neuroplasm,  203 
Neurosome,  203 
Neutral  stains,  25 
Neutrophile  leukocytes,  100 
Nipple,  196 
Nodes  of  Ranvier,  208 
Noma,  360 

Non-medullated  nerve-fibres,  208 
Nuclear  fibrils,  26 

matrix,  26 

membrane,  26 
Nuclei,  23,  26 

function  of,  27 

location  of,  26 

shape  of,  26 

size  of,  27 

structure  of,  26 
Nucleolus,  203 
Nutrition,  pathology  of,  274 

O. 

Odontoblasts,  48 
(Edema,  272 
of  lungs,  338 
varieties  of,  272 
cachectic,  273 
cardiac,  272 
localized,  273 


(Edema,  renal,  273 
(Esophagus,  125 

inflammation  of,  365 

mucous  membrane  of,  125 
epithelium,  125 
submucosa,  125 
tunica  propria,  125 

muscular  layer,  125 
Olfactory  cells,  142 

terminals,  224 
Oligemia,  309 
Oogenesis,  186 
Organs,  74 

cells  of,  74 

of  Corti,  235,  238 

parenchyma  74 

sustentacular  tissue,  74 
Ossification,  58 
Osteoblasts,  59 
Osteoclasts,  58 
Osteoma,  293 
Ova,  23,  64,  183 
Ovary,  182 

epithelial  covering  of,  183 

stroma  of,  183 
Oviducts,  186 
Ovulation,  184 
Ovule,  38,  J84 

fertilization  of,  39 

maturation  of,  38 

structure  of,  38 
Oxyphile  leucocytes,  100 

P. 

Pachymeningitis,  420 

chronic,  420 

hemorrhagic,  420 
Palate,  soft,  124 
Pancreas,  138 

atrophy  of,  401 

carcinoma  of,  401 

connective  tissue  of,  138 

inflammation  of,  401 
Papilla?  of  tongue,  117 

circumvallate,  118 

filiform,  118 

foliate,  119 

fungiform,  118 
Papilloma,  299 

of  bladder,  417 
Papillomata  of  larynx,  333 


454 


INDEX. 


Parathyroids,  108 
Parenchymatoufc.  degeneration,  281 

of  kidney,  412 
inflammation,  259 
Parotid  gland,  120 
Pathogenic  bacteria,  269 
Pathology,  human,  243 

modern  or  cellular,  244 
Pelvis  of  kidney,  168 

wall  of,  168 
Penis,  179 
Peptic  or  cardiac  glands  of  stomach, 

Pericarditis,  326 
Pericardium,  76 
fibrous,  76 
serous,  76 
Perimysium,  61 
Periosteum,  57 
Peritoneum,  133 
inflammation  of,  401 
tuberculosis  of,  402 
Peritonitis,  401 
chronic,  402 
Peyer's  patches,  131 
Phagocytosis,  101,  252 
Pharyngeal  aponeurosis,  124 

tonsil,  124 

Pharyngitis,  pseudomembranous,  361 
Pharynx,  124,  143 
diseases  of,  361 
diphtheria,  361 
pseudomembranous  pnaryngitis, 

361 
simple  catarrhal    inflammation, 

361 

tonsillitis,  363 
mucous  membrane  of,  124 
epithelial  lining,  124 
lymphoid  nodules,  124 
submucosa,  124 
tunica  propria,  124 
walls  of,  124 
Phlebitis,  330 
chronic,  331 
Phthisis,  acute,  350 
chronic,  353 
fibroid,  354 
Pia  mater,  211 
Pigmentary  infiltration,  283 
extrinsic,  284 
intrinsic,  283 


Pigmented  epithelium,  46 
Pineal  body,  110 
Pituitary  body,  110 

anterior  lobe  of,  110 
posterior  lobe  of,  110 
Placenta,  192 
Plasma-cells,  48 
Plethora,  309 
Pleura,  150 
diseases  of,  356 
empyema  of,  351 
hsemothorax,  356 
hydrothorax,  356 
pleuritis,  357 
pneumothorax,  356 
Pleuritis,  357 
fibrinous,  357 
serofibrinous,  357 
Plexus  of  Auerbach,  132 

of  Meissner,  132 
Pneumonia,  339 

chronic  interstitial,  345 
lobar,  339 

division  of  process.  340 
etiology  of,  340 
lobular,  343 
etiology  of,  343 
lesions  of,  344 
Pneumothorax,  356 
Polar  body,  49 
corpuscle,  27 
Poliomyelitis,  acute  anterior,  438 

chronic  anterior,  435 
Polymorphonuclear  leukocytes,  100 
Polynuclear  leukocytes,  100 
Pons,  213 
Portal  vein,  136 
Productive  inflammation,  259 
Pronucleus,  female,  39 

male,  40 
Prostate  gland,  178 

sustentacular    connective    tissue, 

178 

Protoplasm,  22 
granules,  24,  25 
vacuoles,  24 

Protoplasmic  processes,  205 
Pseudomembranous  pharyngitis,  361 

stomatitis,  359 
Purkinje,  cells  of,  213 
Purulent  inflammation,  256 
Pyelitis,  415 


INDEX. 


455 


Pyelo-nephritis,  415 
Pyloric  glands  of  stomach,  127 
Pyonephrosis,  415 
Pyramidal  lobules  of  lung,  415 
Pyramids  of  Ferrein,  160 
'of  Malpighi,  158 


Quinsy,  364 


K. 


230 


33,  41 


Radiating  fibres  of  Miiller, 
Ranvier,  nodes  of,  208 
Rectum,  133 
Red-marrow,  57 
Renal  calculi,  416 

dropsy,  273 
Repair,  259 
Reproduction, 

of  cells,  33 

sexual,  38 

Reproductive  system,  172 
Respiratory  organs,  diseases  of,  332 

system,  141 

general  considerations  of,  141 
Retention  cysts,  308 
Retiform  tissue,  52 
Retina,  230 
Rhabdomyomata,  304 
Rhinitis,  332 

acute,  332 

chronic,  332 
Rhinoscleroma,  267 
Round-celled  sarcomata,  295 

S. 

Saccular  glands,  compound,  70 

simple,  70 
Saccule,  235 
Saliva,  122 
Salivary  glands,  120 

blo'odvessels  of,  120 

ducts  of,  120 

general  structure  of,  120 

inflammation  of,  365 

lymphatics  of,  120 

nerve  filaments  of,  120 

sustentacular    connective     tissue 

of,  120 
Salter,  incremental  lines  of,  115 


Saprophytic  bacteria,  269 
Sarcoleinma,  60 
Sarcoma,  294 

alveolar,  297 

angeiosarcomata,  297 

of  brain,  428 

endothelial,  298 

giant-celled  or  myeloid,  297 

of  larynx,  333 

melanotic,  298 

of  mouth,  360 

primary,  of  kidney,  414 

round-celled,  295 

spindle-celled,  296 

of  urethra,  419 
Sarcoplasm,  61 
Sarcous  discs.  62 

elements.  62 

substance,  61 
Scala  media,  237 
Schreger,  lines  of,  115 
Sclerosis,  amy trophic  lateral,  435 

of  posterior  columns,  431 

spontaneous  lateral,  434 
Sebaceous  glands,  157 
Secretions,  external,  68 

internal,  68 
Secretory  glands,  67 

morphology  of,  70 
Segmentation,  34 
Semen,  65,  181 
Semicircular  canals,  236 
Seminal  vesicle,  177 
Serous  exudate,  functions  of,  255 

glands,  71 

of  tongue,  117 

membranes,  73 
Sertoli,  columns  of,  174 
Sharpey,  fibres  of,  57 
Sneath'of  Schwann,  208 
Simple  fluids,  65 
Sinuses-lymph,  87 

vascular,  80 

venous,  79 

Skeletal  structures,  198 
Skin,  151 
Soft  palate,  124 
Specialized  epithelium  46 
Spermatogenesis,  174 
Spermatozoa,  181 
Spheroidal-celled  cancer,  302 
Spinal  cord,  214 


,56 


INDEX. 


Spinal  cord,  hemorrhage  of,  429 

nerve  cells  of,  215 
Spindle-celled  sarcoma,  296 
Spiral  ganglion,  240 
Spleen,  104 

bloodvessels  of,  105 
function  of,  106 
general  structure,  104 
lymphatic  vessels  of,  106 
sustentacular  framework  of,  105 
Splenic  pulp,  105 
Spongioplasm,  24 
Spores,  23 
Squamous-celled  cancer,  303 

epithelium,  43 
Stains,  acid,  24 
basic,  24 
neutral,  25 
Stomach,  126 

bloodvessels  of,  128 
diseases  of,  366 
gastrectasia,  366 
gastritis,  366 
acute  toxic,  367 
chronic,  368 
purulent,  367 
simple  acute,  366 
gastroptosis,  366 
tumors,  375 
ulcers,  371 

lymphatic  vessels  of,  128 
mucosa  of,  126 

epithelial  lining,  126 
muscular  coat,  128 
peptic  or  cardiac  glands,  126 
pyloric  glands,  127 
serous  or  peritoneal  coat,  128 
subepithelial  connective  tissue  of, 

127 

submucosa,  128 
walls  of,  126 
Stomatitis,  359 
aphthous,  359 
catarrhal,  359 
croupous,  359 
gangrenous,  360 
pseudomembranous,  359 
ulcerous,  359 
Stratum  corneum,  153 
granulosum,  152 
lucidum,  153 
Malpighii,  152 


Sublingual  gland,  121 
Submaxillary  gland,  122 
Submucosa,  72 

Suppurative  inflammation,  256 
Suprarenal  glands.      See   Adrenal 

glands. 

Suspensory  ligament,  229 
Sustentacular  tissue,  87 
Sweat-glands,  154 
Synarthrosis,  200 
Synovial  membranes,  199 
Syphilis,  267 

of  brain,  428 

of  intestines,  391 

of  kidneys,  413 

of  larynx,  333 

of  liver,  399 

of  lungs,  355 

of  meninges,  424 

of  mouth,  360 

of  nose,  332 

T. 

Tactile  cells,  221 
Taste-buds,  119 

-terminals,  224 

Technique,  dyes,  20 

general,  21 

nuclear,  20 

histological,  20 

sections,  20 
Teeth,  112 

crusta  petrosa,  114 

dentine,  114 

development  of,  115 

enamel  of,  113 

general  structure  of,  112 

pulp-cavity,  115 
Teledendrites,  205 
Tendons,  198 
Tendon-sheaths,  199 
Teratoma,  307 
Terminal  bronchioles,  148 
Testicle,  172 

seminiferous  tubules,  173 

sustentacular  connective  tissue  of, 

173 

Thoracic  duct,  85 
Thrombosis,  270 

appearance  and  structure  of,  270 

of  brain,  424 


INDEX. 


457 


Thrombosis,  cause  of,  271 
Thrush,  360 
Thymus  gland,  88 
Thyroid  gland,  107 

bloodvessels  of,  107 
functions  of,  108 
lymphatics  of,  108 
sustentacular  connective  tissue  of, 

107 

Tissues,  20,  22,  42 
adenoid,  85 
adipose,  52 
areolar,  50 
classes  of,  42 

connective  tissue,  47 
endothelium,  42,  46 
epithelium,  42 
free  cells  and  body  fluid,  64 
muscles.  60 
nerve-,  64 

connective,  varieties  of,  49 
adipose,  52 
areolar,  50 
bone,  56 
cartilage,  52 
membrane?,  51 
basement,  52 
distant,  51 
mucous,  49 
retiform,  52 
white  fibrous,  51 
yellow  elastic,  51 
elements  of,  21 
erectile,  81 
fatty,  52 
lymphoid,  85 
mucous,  49 
nerve-,  64 
retiform,  52 
adenoid,  52 
lymphoid,  52 
sustentacular,  87 
white  fibrous,  51 
yellow  elastic,  51 
To'ngue,  116 

general  structure  of,  116 
glands  of,  117 
mucous,  117 
serous,  117 

lymphoid  tissue  of,  117 
mucous  membrane  of,  116 
epithelial  covering,  116 


Tongue,  mucous  membrane,  submu- 

cosa,  116 
tunica  propria,  116 

muscular  substance  of,  116 

papilla?  of,  117 
circumvallate,  118 
filiform,  118 
foliate,  119 
fungiform,  118 
Tonsillitis,  363 
Tonsils,  90,  122 

crypts  of,  1 22 

lyraphoid  cells  of,  122 

mucous  glands  of,  122 
Trachea,  144 

mucous  membrane  of,  144 
Transitional  epithelium,  44 

leukocytes,  99 
Tuberculosis,  264 

of  bladder,  417 

of  brain,  427 

caseation,  266 

fibroid  transformation,  266 

giant-cell,  266 

histological  tubercle,  264 

of  intestines,  390 

of  kidneys,  413 

of  larynx,  333 

of  liver,  399 

of  lungs,  347 

acute  miliary.  349 

of  meninges,  423 

of  mouth,  360 

of  peritoneum,  402 
Tubular  glands,  compound,  70 

simple,  70 
Tumors,  286 

of  bladder,  417 

of  brain,  428 

classification  of  287 
histological,  2S8 

of  cord,  440 

definition  of,  286 

etiology  of,  286 

of  intestines,  392 

of  kidneys,  414 

of  liver,  399 

of  lungs,  356 

of  meninges,  424 

of  mouth,  3(>0 

of  stomach,  375 

of  urethra,  419 


458 


INDEX. 


Tunica  adventitia,  78,  79 

intima,  77,  79 

media,  77,  79 
Typhoid  fever,  386 
Tyson,  glands  of,  180 

U. 

Ulcer  of  stomach,  371 
Umbilical  cord,  193 

vesicle,  191 
Ureter,  168 

coats  of,  168 
fibrous,  168 
mucous,  168 
muscular,  168 
Urethra,  169 

female,  169 

inflammation  of,  418 

male,  170 

muscular  coat  of,  170 

stricture  of,  419 

tumors  of,  419 
Urethritis,  acute,  418 

chronic,  418 
Urinary  bladder,  416 

organs,  158 

diseases  of,  403 
Urine,  171 

secretion  of,  167 
Uriniferous  tubule,  162 

neck  of,  1 64 
Uterine  glands,  188 
Uterus,  187 

cervix  of,  189 

mucous  membrane  of,  187 

muscular  coat  of,  188 
Utricle,  235 


Vagina,  193 

Varix,  331 

Vas  deferens,  177 

Vasa  eflerentia,  175 

Vascular  emphysema,  336 

sinuses,  80 
Veins,  79 

valves,  79 

tunica  adventitia,  79 
intima,  79 
media,  79 
Venous  sinuses,  79 
Ventricles  of  brain,  213 
Vessel  walls,  increased  permeability 

of,  251 

Vestibule  of  ear,  235 
Villi,  129,  192 

function  of,  130 
Vitreous  body,  230 
Volvulus,  380 
Vulva,  194 

W. 

Wagner,  tactile  corpuscles  of,  221 
Wandering  cells,  49,  64 
Watney's  nodes,  130 
Waxy  casts,  407 

degeneration,  277 
White  fibres,  49 

tibro-cartilage,  54 

fibrous  tissue,  51 

Y. 

Yellow  elastic  cartilage,  55 
fibres,  49 
tissue,  51 
marrow,  58 


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INDEX. 

ANATOMY.__Gray,  p.  11  ;  Treves,  30  ;  Gerrish,  11;  Brockway,  4. 

DICTIONARIES.     Dunglison,  p.  8 ;  Duane,  8  ;  National,  4. 

PHYSICS.     Draper,  p.  8  ;  Robertson,  24  ;  Martin  &  Rockwell,  20. 

PHYSIOLOGY.     Foster,   p.  10;   Chapman,  5;  Schofield,  25;  Collins 
&  Rockwell,  6.  [Luff,  19  ;  Rerasen,  24. 

CHEMISTRY.      Simon,  p.  26  ;  Attfield,  3  ;  Martin  &  Rockwell,  20; 

PHARMACY.     Caspari,  p.  5.  [Brace,  4  :  Scbleif,  25. 

MATERIA   MEDICA.     Calbretb,  p.  6  ;   Maisch,  19  ;  Farquharson,  9  ; 

DISPENSATORY.    National,  p.  21. 

THERAPEUTICS.      Hare,  p.  13  ;  Fothergill,  10  ;  Whitla,  31  ;  Hayem 
&  Hare,  14  ;  Bruce,  4 ;  Schleif,  25  ;  Cashny,  6. 

PRACTICE.     Flint,  p.  9  ;  Loomis  &  Thompson,  19  ;  Malsbary,  20. 

DIAGNOSIS.    Musser,  p.  21 ;  Hare,  12;  Simon,  25;  Herrick,  15;  Hutchi- 
son &  Rainey,  16  ;  Collins,  6. 

CLIMATOLOGY.    Solly,  p.  26  ;  Hayem  &  Hare,  14. 

NERVOUS  DISEASES.     Dercum,  p.  7  ;    Gray,  11 ;  Potts,  23. 

MENTAL  DISEASES.     Clouston,  p.  5  ;  Savage,  24  ;  Folsorn,  10. 

BACTERIOLOGY.       Abbott,  p.  2  ;    Vaughan  &  Novy,  30  ;    Senn's 
(Surgical),  25.      Park,  22  ;  Coates,  6.  [Vale,  21. 

HISTOLOGY.     Klein,  p.  17  ;  Schafer's,  25  ;    Dunham,  8  ;  Nichols  & 

PATHOLOGY.    Green,  p.  12;  Gibbes,  10;  Coats,  6;  Nichols  &  Vale,  21 

SURGERY.     Park,  p.  22 ;  Dennis,  7 ;  Roberts,  24 ;  Ashhurst,  3 ;  Troves,  29 ; 
Cheyne  &  Burghard,  5  ;  Gallaudet,  10. 

SURGERY— OPERATIVE.    Stimson,  p.  27  ;  Smith,  26  ;  Treves,  29. 

SURGERY— ORTHOPEDIC.    Young,  p.  31 ;  Gibney,  10. 

SURGERY— MINOR.    Wharton,  p.  30.  [BalleDger  & 

FRACTURES  and  DISLOCATIONS.   Stimson,  p.  27.  [Wippern,  3. 

OPHTHALMOLOGY.    Norris  &  Oliver,  p.  21 ;  Nettleship,  21 ;  Juler,  17; 

OTOLOGY.  Politzer,  p.  23;  Burnett,  5;  Field,  9;  Bacon,  4. 

LARYNGOLOGY  and  RHINOLOGY.  Coakley,  p.  6  ; 

DENTISTRY.     Essig  (Prosthetic),  p.  9  ;  Kirk  (Operative),  17  ;  Ameri- 
can System.  2  ;  Coleman,  6;  Burchard  4. 

URINARY  DISEASES.    Roberts,  p.  24  ;  Black,  4  ;  Morris,  20. 

VENEREAL    DISEASES.      Taylor,  p.  28  ;    Hayden,  14  ;    Cornil,  6  ; 
Likes,  19. 

SEXUAL  DISORDERS.    Fuller,  p.  10  ;  Taylor,  29. 

DERMATOLOGY.      Hyde,  p.  16  ;  Jackson,  16  ;  Pye-Smith,  24  ;  Mor- 
ris, 20  ;  Jamieson,  16 ;  Hardaway,  12  ;  Grindon,  12. 

GYNECOLOGY.      American   System,  p.  3  ;    Thomas    &   Maude",  29 
Emmet,  9  ;  Davenport,  7  ;  May,  20  ;  Dudley,  8  ;  Crockett,  6. 

OBSTETRICS.     American  System,'  p.  3  ;   Davis,  7  ;   Parvin,  22  ;   Play- 
fair,  23  ;  King,  17  ;  Jewett,  17  ;  Evans,  9. 

PEDIATRICS.    Smith,  p.  26  ;  Thomson,  29  ;  Williams,  31  ;  Tuttle,  30. 

HYGIENE.     Egbert,  p.  9  ;  Richardson,  24  ;  Coates,  6. 

MEDICAL  JURISPRUDENCE.    Taylor,  p.  28. 

QUIZ  SERIES,  POCKET  TEXT-BOOKS  and  MANUALS. 

Pp.  18,  25  and  27. 
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The  International  Dental  Journal. 


any  student  can  take  up 
ing  or  after  college. — Dominion  Den- 
tal Journal. 


OPERATIVE  DENTISTRY.  Edited  by  EDWARD  C.  KIRK,  D.D.S. , 
Professor  of  Clinical  Dentistry,  Department  of  Dentistry,  University 
of  Pennsylvania.  699  pages,  751  engravings.  Cloth,  $5.50 ;  leather, 
$6.50.  Net.  Just  ready. 


Written  by  a  number  of  practi- 
tioners as  well  known  at  the  chair 
as  in  journalistic  literature,  many  of 
them  teachers  of  eminence  in  our 
colleges.  It  should  be  included  in 
the  list  of  text-books  set  down  as 
most  useful  to  the  college  student,— 
The  Dental  News, 


It  is  replete  in  every  particular 
and  treats  the  subject  in  a  progressive 
manner.  It  is  a  book  that  every 
progressive  dentist  should  possess, 
and  we  can  heartily  recommend  it 
to  the  profession, — The  Ohio  Dental 
Journal, 


LEA  BROTHERS  &  Co.,  PHILADELPHIA  AND  NEW  YORK.      3 

AMERICAN  SYSTEMS  OF  GYNECOLOGY  AND  OBSTET- 
RICS. In  treatises  by  the  most  eminent  American  specialists.  Gyne- 
cology  edited  by  MATTHEW  D.  MANN,  A.  M.,  M.  D.,  a^d  Obstetrics 
edited  by  BARTON  C.  HIRST,  M.  D.  In  four  large  octavo  volumes 
comprising  3612  pages,  with  1092  engravings,  and  8  colored  plates.  Per 
volume,  cloth,  $5  ;  leather,  $6 ;  half  Russia,  $7.  For  sale  by  subscrip- 
tion only.  Prospectus  free  on  application  to  the  Publishers. 

AMERICAN  TEXT-BOOK  OF  ANATOMY.     See  Gerrish,  page  11. 

ALLEN  (HARRISON).  A  SYSTEM  OF  HUMAN  ANATOMY; 
WITH  AN  INTRODUCTORY  SECTION  ON  HISTOLOGY,  by 
E.  O.  SHAKESPEARE,  M.D.  Comprising  813  double-columned  quarto 
pages,  with  380  engravings  on  stone,  109  plates,  and  241  wood  cuts 
in  the  text.  In  six  sections,  each  in  a  portfolio.  Price  per  section,  $3.50. 
Also,  bound  in  one  volume,  cloth,  $23.  Sold  by  subscription  only. 

A  PRACTICE  OF  OBSTETRICS  BY  AMERICAN  AU- 
THORS. See  Jeirett,  page  17. 

A  TREATISE   ON  SURGERY  BY  AMERICAN  AUTHORS. 

FOR  STUDENTS  AND  PRACTITIONERS  OF  SURGERY  AND 
MEDICINE.  Edited  by  ROSWELL  PARK,  M.D.  See  page  22. 

ASHHURST  (JOHN,  JR.).  THE  PRINCIPLES  AND  PRACTICE 
OF  SURGERY.  For  the  use  of  Students  and  Practitioners.  Sixth 
and  revised  edition.  In  one  large  and  handsome  octavo  volume  of 
1161  pages,  with  656  engravings.  Cloth,  $6;  leather,  $7. 

As  a  masterly  epitome  of  what  has  j  text-book,  we  do  not  know  its  equal, 
been  said  and  "done  in  surgery,  as  a  It  is  the  best  single  text-book  of 
succinct  and  logical  statement  of  the  surgery  that  we  have  yet  seen  in  this 
principles  of  the  subject,  as  a  model  country. — New  York  Post- Graduate. 

A  SYSTEM  OF  PRACTICAL.  MEDICINE  BY  AMERICAN 
AUTHORS.  Edited  by  WILLIAM  PEPPER,  M.  D.,  LL.  D.  In  five 
large  octavo  volumes,  containing  5573  pages  and  198  illustrations.  Price 
per  volume,  cloth,  $5 ;  leather  $6 ;  half  Russia,  $7.  Sold  by  subscrip- 
tion only.  Prospectus  free  on  application  to  the  Publishers. 

ATTFIELD  (JOHN).    CHEMISTRY :  GENERAL,  MEDICAL  AND 

PHARMACEUTICAL.  New  (16th)'  edition,  specially  revised  by  the 
Author  for  America.  In  one  handsome  12mo.  volume  of  784  pages, 
with  88  illustrations.  Cloth,  $2.50,  net. 

It  is  replete  with  the  latest  inform-  been  adopted,  bringing  the  work  into 

ation,  and  considers  the  chemistry  of  close  touch  with  the  latest   United 

every  substance  recognized  officially  States  Pharmacopoeia,  of  which  it  is 

or  in  general  practice.    The  modern  a  worthy  companion. —  ThePittsburg 

scientific  chemical  nomenclature  has  Medical  Review. 

BALLiENGER  (W.  L.)  AND  WIPPERN  (A.  G.).  Shortly.  A 
POCKET  TEXT-BOOK  OF  DISEASES  OF  THE  EYE,  EAR, 
NOSE  AND  THROAT.  In  one  handsome  12mo.  volume  of  about 
400  pages,  with  many  illustrations.  Cloth,  $1.50,  net.  Lea's  Seric*  of 
Pocket  Text-books,  edited  by  BERN  B.  GALLAUDET,  M.  D.  See  p.  18. 

BARNES  (ROBERT  AND  FANCOURT).    A  SYSTEM  OF  OB- 
STETRIC MEDICINE  AND  SURGERY.    Octayo.  372  pages,  with 
CJoth,  $5; 


4       LEA  BROTHERS  &  Co.,  PHILADELPHIA  AND  NEW  YORK. 

BACON  (GORHAM).  ON  THE  EAR.  One  12mo.  volume,  400  pages, 
109  engravings  and  a  colored  plate.  Cloth,  net,  $2.00.  Just  ready. 

It  is  the  best  manual  upon  otology,    dents  of  medicine — Cleveland  Jour- 
An  intensely  practical  book  for  stu-    nal  of  Medicine. 

BARTHOLOW  (ROBERTS).  CHOLERA;  ITS  CAUSATION,  PRE- 
VENTION AND  TREATMENT.  In  one  12mo.  volume  of  127  pages, 
with  9  illustrations.  Cloth,  $1.25. 

BARTHOLOW  (ROBERTS).  MEDICAL  ELECTRICITY.  A 
PRACTICAL  TREATISE  ON  THE  APPLICATIONS  OF  ELEC- 
TRICITY TO  MEDICINE  AND  SURGERY.  Third  edition.  In 
one  octavo  volume  of  308  pages,  with  110  illustrations. 

BELLi  (F.  JEFFREY).  COMPARATIVE  ANATOMY  AND  PHYS- 
IOLOGY. In  one  12mo.  volume  of  561  pages,  with  229  engravings. 
Cloth,  $2.  See  Students'  Series  of  Manuals,  page  27. 

BILLINGS  (JOHN  S.).  THE  NATIONAL  MEDICAL  DICTIONARY. 
Including  in  one  alphabet  English,  French,  German,  Italian  and 
Latin  Technical  Terms  used  in  Medicine  and  the  Collateral  Sciences. 
In  two  very  handsome  imperial  octavo  volumes  containing  1574 
pages  and  two  colored  plates.  Per  volume,  cloth,  $6 ;  leather,  $7 ; 
naif  Morocco,  $8.50.  For  sale  by  subscription  only.  Specimen  pages 
on  application  to  the  publishers. 

BLACK  (D.  CAMPBELL).  THE  URINE  IN  HEALTH  AND 
DISEASE,  AND  URINARY  ANALYSIS,  PHYSIOLOGICALLY 
AND  PATHOLOGICALLY  CONSIDERED.  In  one  12mo.  volume 
of  256  pages,  with  73  engravings.  Cloth,  $2.75. 


Concise,  practical,  clinical,  well 
illustrated  and  well  printed. — Mary- 
land Medical  Journal. 


A  concise,  yet  complete  manual, 
treating  of  the  subject  from  a  prac- 
tical and  clinical  standpoint. — The 
Ohio  Medical  Journal. 

BLOXAM  (C.  L.).  CHEMISTRY,  INORGANIC  AND  ORGANIC. 
With  Experiments.  New  American  from  the  fifth  London  edition. 
In  one  handsome  octavo  volume  of  727  pages,  with  292  illustrations. 
Cloth,  $2 ;  leather,  $3. 

BROCKWAY  (F.  J.).  A  POCKET  TEXT-BOOK  OF  ANATOMY. 
In  one  handsome  12mo.  volume  of  about  400  pages,  with  many  illus- 
trations. Shortly.  Cloth,  $1.50,  net.  Lea's  Series  of  Pocket  Text-books, 
edited  by  BERN  B.  GALLAUDET,  M.  D.  See  page  18. 

BRUCE  (J.  MITCHELL).  MATERIA  MEDICA  AND  THERA- 
PEUTICS. New  (6th)  edition.  In  one  12mo.  volume  of  600  pages. 
Just  ready.  Cloth,  $1.50,  net.  See  Student's  Series  of  Manuals, 
page,  27. 

PRINCIPLES  OF  TREATMENT.  In  one  octavo  volume.  Pre- 
paring. 

BRYANT  (THOMAS).  THE  PRACTICE  OF  SURGERY.  Fourth 
American  from  the  fourth  English  edition.  In  one  imperial  octavo  vol. 
of  1040  pages,  with  727  illustrations.  Cloth,  $6.50 ;  leather,  $7.50. 

BURCHARD  (HENRY  H.).  DENTAL  PATHOLOGY  AND  THER- 
APEUTICS. Handsome  octavo,  575  pages,  with  400  illustrations. 
Just  ready.  Cloth,  net,  $5.00 ;  leather,  net,  $6.00. 


In  the  treatment  of  the  subject 
the  method  pursued  by  the  author 
js  logical  and  sequential.  The  work 


is  a  valuable  text-book  on  a  subject 
which  has  heretofore  not  been  ade- 
quately rep  resented.  -Dental  Cosmos, 


LEA  BROTHERS  &  Co.,  PHILADELPHIA  AND  NEW  YOBK.       5 

BURNETT  (CHARLES  H.).  THE  EAR :  ITS  ANATOMY,  PHYSI- 
OLOGY AND  DISEASES.  A  Practical  Treatise  for  the  Use  of 
Students  and  Practitioners.  Second  edition.  In  one  8vo.  volume  of 
580  pages,  with  107  illustrations.  Cloth,  $4 ;  leather,  $5. 

CARTER  (R.  BRUDENELL)  AND  FROST  (W.  ADAMS).  OPH- 
THALMIC SURGERY.  In  one  pocket-size  12mo.  volume  of  559 
pages,  with  91  engravings  and  one  plate.  Cloth,  $2.25.  See  Series  of 
Clinical  Manuals,  page  25. 

CASPARI  (CHARLES  JR.).  A  TREATISE  ON  PHARMACY. 
For  Students  and  Pharmacists.  In  one  handsome  octavo  volume  of 
680  pages,  with  288  illustrations.  Cloth,  $4.50. 

The  author's  duties  as   Professor  student  who  cannot  understand  must 

of  Theory  and  Practice  of  Pharmacy  be  dull  indeed.    The  book  is  full  of 

in  the  Maryland  College  of  Phar-  new,  clean,  sharp  illustrations,which 

macy,  and  his  contact  with  students  tell  the  story  frequently  at  a  glance, 

made    him    aware    of   their    exact  The  index  is  full  and  accurate. — 

wants  in  the  matter  of  a   manual.  National  Druggist. 
His    work    is  admirable,  and  the  1 

CHAPMAN  (HENRY  C.).  A  TREATISE  ON  HUMAN  PHYSI- 
OLOGY. New  (2d)  edition.  In  one  octavo  volume  of  921  pages, 
with  595  illustrations.  Just  ready.  Cloth,  $4.25 ;  leather,  $5.25,  net. 


In  every  respect  the  work  fulfils 
its  promise,  whether  as  a  complete 
treatise  for  the  student  or  as  an  ad- 


mirable work  of  reference  for  the 
physician. — North  Carolina  Medical 
Journal. 


CHARLES  (T.  CRANSTOUN).  THE  ELEMENTS  OF  PHYSIO- 
LOGICAL AND  PATHOLOGICAL  CHEMISTRY.  Octavo,  451 
pages,  with  38  engravings  and  1  colored  plate.  Cloth,  $3.50. 

CHEYNE  (W.  WATSON).    THE    TREATMENT    OF    WOUNDS, 
.  ULCERS  AND  ABSCESSES.    In  one  12nio.  volume  of  207  pages. 
Cloth,  $1.25. 


One  will  be  surprised  at  the 
amount  of  practical  and  useful  in- 
formation it  contains;  information 
that  the  practitioner  is  likely  to 


need  at  any  moment.  The  sections 
devoted  to  ulcers  and  abscesses  are 
indispensable  to  any  physician. — 
The  Charlotte  Medical  Journal. 


CHEYXE  (W.  W.)  AND  BURGH ARD  (F.  F.)  SURGICAL 
TREATMENT.  In  six  octavo  volumes,  illustrated.  Volume  1,  299 
pages  and  66  engravings,  just  ready.  Cloth,  $3.00  net. 

CLARKE  (W.  B.)  AND  LOCKWOOD  (C.  B.).  THE  DISSECTOR'S 
MANUAL.  In  one  12mo.  volume  of  396  pages,  with  49  engravings. 
Cloth,  $1.50.  See  Students'  Series  of  Manuals,  page  27. 

CLELAND  (JOHN).  A  DIRECTORY  FOR  THE  DISSECTION  OF 
THE  HUMAN  BODY.  In  one  12mo.  vol.  of  178  pages.  Cloth,  $1.25. 

CLINICAL  MANUALS.     See  Series  of  Clinical  Manuals,  page  25. 

CLOUSTON  (THOMAS  S.).  CLINICAL  LECTURES  ON  MENTAL 
DISEASES.  New  (5th)  edition.  In  one  octavo  volume  of  750  pages, 
with  19  colored  plates.  Cloth,  $4.25,  net.  Just  ready. 
.^g^FoLSOM's  Abstract  of  Laws  of  U.  S.  on  Custody  of  Insane,  octavo, 
$1.50,  is  sold  in  conjunction  with  Clouston  on  Mental  Diseases  for 
$5.00,  net,  for  the  two  works. 


6      LEA  BBOTHEBS  &  Co.,  PHILADELPHIA  AND  NEW. YORK. 

CLOWES  (FRANK).  AN  ELEMENTARY  TREATISE  ON  PRACTI- 
CAL CHEMISTRY  AND  QUALITATIVE  INORGANIC  ANALY- 
SIS. From  the  fourth  English  edition.  In  one  handsome  12mo. 
volume  of  387  pages,  with  55  engravings.  Cloth,  $2.50. 

COAKLEY  (CORNELIUS  G.).  THE  DIAGNOSIS  AND  TREAT- 
MENT OF  DISEASES  OF  THE  NOSE,  THROAT,  NASO- 
PHARYNX AND  TRACHEA.  In  one  12mo.  volume  of  about  400 
pages,  fully  illustrated.  Preparing, 

COATES  (W.  E.,  JR.).  A  POCKET  TEXT-BOOK  OF  BACTE- 
RIOLOGY AND  HYGIENE.  In  one  handsome  12mo.  volume  of 
about  350  pages,  with  many  illustrations.  Shortly,  Cloth,  $1.50,  net. 
Lea's  Series  of  Pocket  Text-books,  edited  by  BERN  B.  GALLAUDET, 
M.  D.  See  page  18. 

COATS  (JOSEPH).  A  TREATISE  ON  PATHOLOGY.  In  one  vol. 
of  829  pages,  with  339  engravings.  Cloth,  $5.50 ;  leather,  $6.50. 

COLEMAN  (ALFRED).  A  MANUAL  OF  DENTAL  SURGERY 
AND  PATHOLOGY.  With  Notes  and  Additions  to  adapt  it  to  Amer- 
ican Practice.  By  THOS.  C.  STELLWAGEN,  M.A.,  M.D.,  D.D.S.  In  one 
handsome  octavo  vol.  of  412  pages,  with  331  engravings.  Cloth,  $3.25. 

COLLINS  (C.  P.).  A  POCKET  TEXT-BOOK  OF  MEDICAL 
DIAGNOSIS.  In  one  handsome  12mo.  volume  of  about  350  pages, 
with  many  illustrations.  Shortly.  Cloth,$1.50,  net.  Lea's  Series  of  Pocket 
Text-books,  edited  by  BEEN  B.  GALLAUDET,  M.  D.  See  page  18. 

COLLINS  (H.  D.)  AND  ROCKWELL  (W.  H.).  A  POCKET 
TEXT-BOOK  OF  PHYSIOLOGY.  In  one  handsome  12mo.  volume 
of  about  300  pages,  with  many  illustrations.  Cloth,  $1.50,  net.  In  press. 
Lea's  Series  of  Pocket  Text-books,  edited  by  BEEN  B.  GALLAUDET, 
M.  D.  See  page  18. 

CONDIE  (D.  FRANCIS).  A  PRACTICAL  TREATISE  ON  THE  DIS- 
EASES OF  CHILDREN.  Sixth  edition,  revised  and  enlarged.  In 
one  large  8vo.  volume  of  719  pages.  Cloth,  $5.25 ;  leather,  $6.25. 

CORNIL  (V.).  SYPHILIS:  ITS  MORBID  ANATOMY,  DIAGNO- 
SIS AND  TREATMENT.  Translated,  with  Notes  and  Additions,  by 
J.  HENEY  C.  SIMES,  M.D.  and  J.  WILLIAM  WHITE,  M.  D.  In  one 
8vo.  volume  of  461  pages,  with  84  illustrations.  Cloth,  $3.75. 

CROCKETT  (M.  A.).  A  POCKET  TEXT-BOOK  OF  DISEASES 
OF  WOMEN.  In  one  handsome  12mo.  volume  of  about  350  pages, 
with  many  illustrations.  Cloth,$1.50,  net.  Shortly.  Lea's  Series  of  Pocket 
Text-books,  edited  by  BEEN  B.  GALLAUDET,  M.  D.  See  page  18. 

CROOK  (JAMES  K.)  ON  MINERAL  WATERS  OF  THE 
UNITED  STATES.  Octavo,  575  pages.  Just  ready.  Cloth,  $3.50,  net. 

CULBRETH  (DAVID  M.  R.).  MATERIA  MEDICA  AND  PHAR- 
MACOLOGY. In  one  handsome  octavo  volume  of  812  pages,  with 
445  illustrations.  Cloth,  $4.75. 

adopted  as  the  text-book  in  all  col- 
leges of  pharmacy  and  medicine. 
It  is  one  of  the  most  valuable  works 


A  thorough,  authoritative  and 
systematic  exposition  of  its  most 
important  domain.  —  The  Canada 
Lancet. 

This  work  ought  to  be  at  once 


that  have  been  issued. — The    Ohi 
Medical  Journal. 


CUSHNY    (ARTHUR  R.).   TEXT-BOOK  OF  PHARMACOLOGY. 

Handsome  8vo.,  728  pages,  with  47  illus.  Just  ready.  Cloth,  $3.75,  net. 


LEA  BBOTHKBS  &  Co.,  PHILADELPHIA  AND  NEW  YOEK.       7 

DAI/TON  (JOHN  C.).   A  TKEATISE  ON  HUMAN  PHYSIOLOGY. 

Seventh  edition.     Octavo,   722  pages,  with   252  engravings.    Cloth, 
$5 ;  leather,  $6. 

DOCTRINES  OF  THE  CIRCULATION  OF  THE  BLOOD.  In 


one  handsome  12mo.  volume  of  293  pages.    Cloth,  $2. 

DAVENPORT  (F.  H.).  DISEASES  OF  WOMEN.  A  Manual  of 
Gynecolpgy.  For  the  use  of  Students  and  Practitioners.  New 
(3d)  edition.  In  one  handsome  12mo.  volume  of  387  pages,  with  150 
illustrations.  Cloth,  $1.75,  net.  Just  ready. 

DAVIS  (EDWARD  P.).  A  TREATISE  ON  OBSTETRICS.  FOB 
STUDENTS  AND  PRACTITIONERS.  In  one  very  handsome 
octavo  volume  of  546  pages,  with  217  engravings  and  30  full-page 
plates  in  colors  and  monochrome.  Cloth,  $5 ;  leather,  $6. 


This  work  must  become  the  prac- 
titioner's text-book  as  well  as  the 
student's.  It  is  up  to  date  in  every 
respect. —  Va.  Med.  Semi-Monthly. 

A  work  unequalled  in  excellence. 
— The  Chicago  Clinical  Review. 

Decidedlv  one  of  the  best   text- 


books on  the  subject.  It  is  exception- 
ally useful  from  every  standpoint. — 
Nashville  Jour,  of  Med.  and  Surgery. 
From  a  practical  standpoint  the 
work  is  all  that  could  be  desired.  A 
thoroughly  scientific  and  brilliant 
treatise  on  obstetrics.  —Med.  News. 


DAVIS  (P.  H.).  LECTURES  ON  CLINICAL  MEDICINE.  Second 
edition.  In  one  12mo.  volume  of  287  pages.  Cloth,  $1.75. 

DE  LA  HECHE'S  GEOLOGICAL  OBSERVER.  In  one  large  octavo 
volume  of  700  pages,  with  300  engravings.  Cloth,  $4. 

DENNIS  (FREDERIC  S.)  AND  BHJLINGS  (JOHN  S.).  A  SYS- 
TEM OF  SURGERY.  In  contributions  by  American  Authors. 
Complete  work  in  four  very  handsome  octavo  volumes,  containing 
3652  pages,  with  1585  engravings  and  45  full-page  plates  in  colors 
and  monochrome.  Per  volume,  cloth,  $6.00;  leather,  $7.00;  half 
Morocco,  gilt  back  and  top,  $8.50.  For  sale  by  subscription  only. 
Full  prospectus  free  on  application  to  the  publishers. 

It  is  worthy  of  the  pogition  which  ;  American  surgery  and  is  thoroughly 
surgery  has  attained  in  the  great !  practical. — Annals  of  Surgery. 
Republic  whence    it  comes.  —  The  '      No  work  in  English  can  be  con- 
London  Lancet.  sidered  as  the  rival  of  this. — The 

It  may  be  fairly  said  to  represent    American  Journal  of  the  Medical 
the    most     advanced    condition    of;  Sciences. 

DERCUM  (FRANCIS  X.,  EDITOR).  A  TEXT-BOOK  ON 
NERVOUS  DISEASES.  By  American  Authors.  In  one  handsome 
octavo  volume  of  1054  pages,  with  341  engravings  and  7  colored 
plates.  Cloth,  $6.00  ;  leather,  $7.00.  Net. 

Representing  the  actual  status  of       The  work  is  representative  of  the 

our  knowledge  of  its  subjects,  and  best  methods  of  teaching,  as  devel- 

the  latest  and  most  fully  up-to-date  oped  in  the  leading  medical  colleges 

of  any  of  its  class. — Jour,  of  Amer-  of  this  country. — Alienist  and  Neu- 

ican  Med.  Association.  rologist. 

The  most  thoroughly  up-to-date       The  best  text-book  in  any  Ian- 
treatise  that  we  have  on  this  subject.  I  guage. — The  Medical  Fortnightly. 
— American  Journal  of  Insanity. 

DE  SCHWEINITZ  (GEORGE  E.).  THE  TOXIC  AMBLYOPIAS. 
Their  Classification,  History,  Symptoms,  Pathology  and  Treatment. 
Very  handsome  octavo,  240  pages,  46  engravings,  and  9  full-page 
plates  in  colors.  Limited  edition,  de  luxe  binding,  $4.  Net. 


8      LEA  BROTHERS  &  Co.,  PHILADELPHIA  AND  NEW  YORK. 

DRAPER  (JOHN  C.).  MEDICAL  PHYSICS.  A  Text-book  for  Stu- 
dents and  Practitioners  of  Medicine.  In  one  handsome  octavo  volume 
of  734  pages,  with  376  engravings.  Cloth,  $4. 

DRUITT  (ROBERT).  THE  PRINCIPLES  AND  PRACTICE  OF 
MODERN  SURGERY.  A  new  American,  from  the  twelfth  London 
edition,  edited  by  STANLEY  BOYD,  F.  R.  C.  S.  In  one  large  octavo 
volume  of  965  pages,  with  373  engravings.  Cloth,  $4 ;  leather,  $5. 
DUANE  (ALEXANDER).  THE  STUDENT'S  DICTIONARY  OF 
MEDICINE  AND  THE  ALLIED  SCIENCES.  New  edition.  Com- 
prising the  Pronunciation,  Derivation  and  Full  Explanation  of  Medi- 
cal Terms,  with  much  Collateral  Descriptive  Matter.  Numerous  Tables, 
etc.  Square  octavo  of  658  pages.  Cloth,  $3.00;  half  leather,  $3.25; 
full  sheep,  $3.75.  Thumb-letter  Index,  50  cents  extra. 

convenience    and    thoroughness.  — 
Medical  Record. 

The  best  student's  dictionary. — 
Canada  Lancet. 


Far  superior  to  any  dictionary  for 
the  medical  student  that  we  know  of. 
—  Western  Med.  and  Surg.  Reporter. 

The  book  is  brought  accurately  to 


date.    It  is  a  model  of  conciseness, 

DUDLEY  (E.  C.).  THE  PRINCIPLES  AND  PRACTICE  OF 
GYNECOLOGY.  Handsome  octavo  of  652  pages,  with  422  illustra- 
tions in  black  and  colors.  Cloth,  $5.00,  net ;  leather,  $6.00,  net.  Just 
ready. 


The   book   can  be   safely    recom- 
mended as  a  complete  and  reliable 


tice  of  modern  gynecology. — Inter- 
national Medical  Magazine. 


exposition  of  the  principles  and  prac- 

DUNCAN  (J.  MATTHEWS).  CLINICAL  LECTURES  ON  THE 
DISEASES  OF  WOMEN.  Delivered  in  St.  Bartholomew's  Hospital. 
In  one  octavo  volume  of  175  pages.  Cloth,  $1.50. 

DTJNGLJSON  (ROBLJEY).  A  DICTIONARY  OF  MEDICAL  SCI- 
ENCE. Containing  a  full  explanation  of  the  various  subjects  and 
terms  of  Anatomy,  Physiology,  Medical  Chemistry,  Pharmacy,  Phar- 
macology, Therapeutics,  Medicine,  Hygiene,  Dietetics,  Pathology,  Sur- 
gery, Ophthalmology,  Otology,  Laryngology,  Dermatology,  Gynecol- 
ogy, Obstetrics,  Pediatrics,  Medical  Jurisprudence,  Dentistry,  etc.,  etc. 
Bv  ROBLEY  DUNGLISON,  M.  D.,  LL.  D.,  late  Professor  of  Institutes 
of  Medicine  in  the  Jefferson  Medical  College  of  Philadelphia.  Edited 
by  RICHARD  J.  DUNGLISON,  A.  M.,  M.  D.  Twenty-first  edition,  thor- 
oughly revised  and  greatly  enlarged  and  improved,  with  the  Pronuncia- 
tion, Accentuation  and  Derivation  of  the  Terms.  With  Appendix. 
In  one  magnificent  imperial  octavo  volume  of  1225  pages.  Cloth,  $7  ; 
leather,  $8.  Thumb-letter  Index  for  quick  use,  75  cents  extra. 


The  most  satisfactory  and  authori- 
tative guide  to  the  derivation,  defini- 
tion and  pronunciation  of  medical 
terms. — The  CharlotteMed.  Journal. 

Covering  the  entire  field  of  medi- 
cine, surgery  and  the  collateral 


scarcely  be  measured. — Med.  Record. 
Pronunciation  is  indicated  by  the 
phonetic  system.  The  definitions  are 
unusually  clear  and  concise.  The 
book  is  wholly  satisfactory.—  Uni- 
versity Medical  Magazine. 


sciences,  its  range  of  usefulness  can 

DUNHAM  (EDWARD    K.).      MORBID    AND    NORMAL     HIS- 
TOLOGY.    Octavo,  450  pages,with  363  illustrations.  Cloth,  $3.25,  net. 
Just  ready. 
The  best  one- volume  text  or  refer- 1  of  published  in  America. —  Virginia 

ence  book  on  histology  that  we  know  I  Medical  Semi-Monthly. 

EDES  (ROBERT  T.).  TEXT-BOOK  OF  THERAPEUTICS  AND 
MATERIA  MEDICA.  In  one  8vo.  volume  of  544  pages.  Cloth,  $3.50  ; 
leather,  $4.50. 

EDIS  (ARTHUR  W.).  DISEASES  OF  WOMEN.  A  Manual  for 
Students  and  Practitioners.  In  one  handsome  8vo.  volume  of  576  pages, 
with  148  engravings.  Cloth,  $3 ;  leather,  $4. 


LEA  BROTHERS  &  Co.,  PHILADELPHIA  AND  NEW  YORK.       9 

EGBERT  (SENECA).  A  MANUAL  OF  HYGIENE  AND  SANI- 
TATION. In  one  12mo.  volume  of  359  pages,  with  63  illustrations. 
Just  ready.  Cloth,  Net,  $2.25. 


It  is  written  in  plain  language, 
and,  while  primarily  designed  for 


ligence.     The  writer  has  adapted  it 
to    American    conditions,  and    his 


physicians,  it  can  be  studied  with    suggestions  are,  above  all,  practical, 
profit  by  any  one  of  ordinary  intel-  |  — The  NeivYork  Medical  Journal. 

ELLIS  (GEORGE  VINER).  DEMONSTRATIONS  IN  ANATOMY. 
Eighth  edition.  Octavo,  716  pages,  with  249  engravings.  Cloth, 
$4.25 ;  leather,  $5.25. 

EMMET  (THOMAS  ADDIS).  THE  PRINCIPLES  AND  PRAC- 
TICE OF  GYNAECOLOGY.  Third  edition.  Octavo,  880  pages,  with 
150  original  engravings.  Cloth,  $5 ;  leather,  $6. 

ERICHSEN  (JOHN  E.).  THE  SCIENCE  AND  ART  OF  SUR- 
GERY. Eighth  edition.  In  two  large  octavo  volumes  containing 
2316  pages,  with  984  engravings.  Cloth,  $9 ;  leather,  $11. 

ESSIG  (CHARLES  J.).  PROSTHETIC  DENTISTRY.  See  American 
Text-Books  of  Dentistry,  page  2. 

EVANS  (DAVID  J.).  A  POCKET  TEXT-BOOK  OF  OBSTETRICS. 
In  one  handsome  12mo.  volume  of  about  300  pages,  with  many  illustra- 
tions. Cloth,  $1.50,  net.  Shortly.  Lea's  Series  of  Pocket  Text-books, 
edited  by  BERN  B.  GALLATJDET,  M.  D.  See  page  18. 

FARQUHARSON  (ROBERT).  A  GUIDE  TO  THERAPEUTICS. 
Fourth  American  from  fourth  English  edition,  revised  by  FRANK 
WOODBURY,  M.  D.  In  one  12mo.  volume  of  581  pages.  Cloth,  $2.50. 

FIELD  (GEORGE  P.).  A  MANUAL  OF  DISEASES  OF  THE 
EAR.  Fourth  edition.  In  one  octavo  volume  of  391  pages,  with  73 
engravings  and  21  colored  plates.  Cloth,  $3.75. 

To  those    who    desire    a  concise  j  It  is  just  such  a  work  as  is  needed 
work  on  diseases  of  the  ear,  clear  I  by    every    general   practitioner.  — 
and    practical,    this  manual    com-    American  Practitioner  and  News. 
mends  itself  in  the  highest  degree.  ' 

FLINT  (AUSTIN).  A  TREATISE  ON  THE  PRINCIPLES  AND 
PRACTICE  OF  MEDICINE.  Seventh  edition,  thoroughly  revised 
by  FREDERICK  P.  HENRY,  M.  D.  In  one  large  8vo.  volume  of  1143 
pages,  with  engravings.  Cloth,  $5.00 ;  leather,  $6.00. 

The  work  has  well  earned  its  lead-  i  medicine  in  the  medical  schools. — 
ing  place  in  medical  literature. —    Northwestern  Lancet. 
Medical  Record.  The  best  of  American  text-books 

The  leading  text-book  on  general 

A   MANUAL  OF  AUSCULTATION  AND  PERCUSSION;  of 

the  Physical  Diagnosis  of  Diseases  of  the  Lungs  and  Heart,  and  of 
Thoracic  Aneurism.  Fifth  edition,  revised  by  JAMES  C.  WILSON,  M.  D. 
In  one  handsome  12mo.  volume  of  274  pages,  with  12  engravings. 

A    PRACTICAL   TREATISE    ON    THE    DIAGNOSIS   AND 

TREATMENT  OF  DISEASES  OF  THE  HEART.  Second  edition 
enlarged.  In  one  octavo  volume  of  550  pages.  Cloth,  $4. 

A  PRACTICAL  TREATISE  ON  THE  PHYSICAL  EXPLO- 
RATION OF  THE  CHEST,  AND  THE  DIAGNOSIS  OF  DIS- 
EASES AFFECTING  THE  RESPIRATORY  ORGANS.  Second 
and  revised  edition.  In  one  octavo  volume  of  591  pages.  Cloth,  $4.50. 

MEDICAL  ESSAYS.  In  one  12mo.  vol.  of  210  pages.  Cloth,  $1.38. 

ON  PHTHISIS :  ITS  MORBID  ANATOMY  ETIOLOGY,  ETC. 

A  Series  of  Clinical  Lectures.  In  one  8vo.  volume  of  442  pages. 
Cloth,  $3.50. 


10     LEA  BEOTHEES  &  Co.,  PHILADELPHIA  AND  NEW  YORK. 

FOLSOM  (C.  P.).  AN  ABSTRACT  OF  STATUTES  OF  U.  S. 
ON  CUSTODY  OF  THE  INSANE.  In  one  8vo.  vol.  of  108  pages. 
Cloth,  $1.50.  With  Clouston  on  Mental  Diseases  (new  edition,  see 
page  6)  $5.00,  net,  for  the  two  works. 

FORMULARY,  POCKET,  see  page  32. 

FOSTER  (MICHAEL).    A  TEXT-BOOK  OF  PHYSIOLOGY.    New 

(6th)  and  revised  American  from  the  sixth  English  edition.  In  one 
large  octavo  volume  of  923  pages,  with  257  illustrations.  Cloth,  $4.50 ; 
leather,  $5.50. 

Unquestionably  the  best  book  that  j  This  single  volume  contains  all 
can  be  placed  in  the  student's  hands,  i  that  will  be  necessary  in  a  college 
and  as  a  work  of  reference  for  the  j  course,  and  all  that  the  physician 
busy  physician  it  can  scarcely  be  will  need  as  well.— Dominion  Med. 
excelled.— ThePhila.  Poly  clinic.  \  Monthly. 

FOTHERGILL  (J.  MILNER).  THE  PRACTITIONER'S  HAND- 
BOOK OF  TREATMENT.  Third  edition.  In  one  handsome  octavo 
volume  of  664  pages.  Cloth,  $3.75 ;  leather,  $4.75. 


To  have  a  description  of  the 
normal  physiological  processes  of  an 
organ  and  of  the  methods  of  treat- 
ment of  its  morbid  conditions 
brought  together  in  a  single  chapter, 
and  the  relations  between  the  two 


clearly  stated,  cannot  fail  to  prove 
a  great  convenience  to  many  thought- 
ful but  busy  physicians.  The  prac- 
tical value  of  the  volume  is  greatly 
increased  by  the  introduction  of  many 
prescriptions — New  York  Med.  Jour. 


FOWNES  (GEORGE).  A  MANUAL  OF  ELEMENTARY  CHEM- 
ISTRY (INORGANIC  AND  ORGANIC).  Twelfth  edition.  Em- 
bodying WATTS'  Physical  and  Inorganic  Chemistry.  In  one  royal 
12mo.  volume  of  1061  pages,  with  168  engravings,  and  1  colored 
plate.  Cloth,  $2.75 ;  leather,  $3.25. 

FRANKLAND  (E.)  AND  JAPP  (F.R.).  INORGANIC  CHEMISTRY. 

In  one  handsome  octavo  volume  of  677  pages,  with  51  engravings  and 
2  plates.    Cloth,  $3.75 ;  leather,  $4.75. 

FULLER  (EUGENE).  DISORDERS  OF  THE  SEXUAL  OR- 
GANS IN  THE  MALE.  In  one  very  handsome  octavo  volume  of 
238  pages,  with  25  engravings  and  8  full-page  plates.  Cloth,  $2. 


It  is  an  interesting  work,  and  one 
which,  in  view  of  the  large  and 
profitable  amount  of  work  done  in 
this  field  of  late  years,  is  timely  and 
well  needed. — Medical  Fortnightly. 


tive  and  brings  views  of  sound 
pathology  and  rational  treatment  to 
many  cases  of  sexual  disturbance 
whose  treatment  has  been  too  often 
fruitless  for  good.  —  Annals  of 


The  book  is  valuable  and  instruc-   Surgery. 

FULLER  (HENRY).  ON  DISEASES  OF  THE  LUNGS  AND  AIR 
PASSAGES.  Their  Pathology,  Physical  Diagnosis,  Symptoms  and 
Treatment.  From  second  English  edition.  In  one  8vo.  volume  of  475 
pages.  Cloth,  $3.50. 

GALLAUDET  (BERN  B.).  A  POCKET  TEXT-BOOK  ON  SUR- 
GERY. In  one  handsome  12mo.  volume  of  about  400  pages,  with  many 
illustrations.  Cloth,  $1.50,  net.  Shortly.  Lea's  Series  of  Pocket  Text- 
booh;  edited  by  BERN  B.  GALLAUDET,  M.  D.  See  page  18. 

GANT  (FREDERICK  JAMES).  THE  STUDENT'S  SURGERY.  A 
Multum  in  Parvo.  In  one  square  octavo  volume  of  845  pages,  with 
159  engravings.  Cloth,  $3.75. 

GLBBES  (HENEAGE).  PRACTICAL  PATHOLOGY  AND  MORBID 
HISTOLOGY.  Octavo,  314  pages,  with  60  illustrations.  Cloth,  $2.75. 

G1BNEY  (V.  P.).  ORTHOPEDIC  SURGERY.  For  the  use  of  Practi- 
tioners and  Students.  In  one  8vo.  vol.  profusely  illus.  Preparing. 


LEA  BROTHERS  &  Co.,  PHILADELPHIA  AND  NEW  YORK.     11 


GERRISH  (FREDERIC  H.).  A  TEXT-BOOK  OF  ANATOMY. 
By  American  Authors.  Edited  by  Frederic  H.  Gerrish,  M.  D.  In  one 
imp.  octavo  volume  of  915  pages,  with  950  illustrations  in  black  and 
colors.  Just  ready.  Clth,$6.50;  flexible  waterproof,  $7;  leath.,  $7.50,  net. 

In  this,  the  first  representative  treatise  on  Anatomy  produced  in  America, 
no  effort  or  expense  has  been  spared  to  unite  an  authoritative  text  with  the 
most  successful  anatomical  pictures  which  have  yet  appeared  in  the  world. 

The  editor  has  secured  the  co-operation  of  the  professors  of  anatomy  in 
leading  medical  colleges,  and  with  them  ha8  prepared  a  text  conspicuous 
for  its  simplicity,  unity  and  judicious  selection  of  such  anatomical  facts  as 
bear  on  physiology,  surgery  and  internal  medicine  in  the  most  compre- 
hensive sense  of  those  terms.  The  authors  have  endeavored  to  make  a 
book  which  shall  stand  in  the  place  of  a  living  teacher  to  the  student,  and 
which  shall  be  of  actual  service  to  the  practitioner  in  his  clinical  work, 
emphasizing  the  most  important  subjects,  clarifying  obscurities,  helping 
most  in  the  parts  most  difficult  to  learn,  and  illustrating  everything  by  all 
available  methods. 

GOULD  (A.  PEARCE).     SUKGICAL  DIAGNOSIS.    In  one  12mo. 

vol.  of  589  pages.     Cloth,  $2.  See  Student's  Series  of  Manuals,  p.  27. 

GRAY  (HENRY).    ANATOMY,  DESCRIPTIVE  AND  SURGICAL. 

New  and  thoroughly  revised  American  edition,  much  enlarged  in  text, 
and  in  engravings  in  black  and  colors.  In  one  imperial  octavo  volume 
of  1239  pages,  with  772  large  and  elaborate  engravings  on  wood.  Price 
of  edition  with  illustrations  in  colors  :  cloth,  $7 ;  leather,  $8.  Price 
of  edition  with  illustrations  in  black :  cloth,  $6 ;  leather,  $7. 


This  is  the  best  single  volume 
upon  Anatomy  in  the  English 
language. —  University  Medical  Mag- 
azine. 

Gray's  Anatomy  affords  the  student 
more  satisfaction  than  any  other 
treatise  with  which  we  are  familiar. 
— Buffalo  Med.  Journal. 

The  most  largely  used  anatomical 
text-book  published  in  the  English 
language. — Annals  of  Surgery. 

Particular  stress  is  laid  upon  the 
practical  side  of  anatomical  teach- 


ing, and  especially  the  Surgical 
Anatomy. — Chicago  Med.  Recorder. 

Holds  first  place  in  the  esteem  of 
both  teachers  and  students. — The 
Brooklyn  Medical  Journal. 

The  foremost  of  all  medical  text- 
books.— Medical  Fortnightly. 

Gray's  Anatomy  should  be  the 
first  work  which  a  medical  student 
should  purchase,  nor  should  he  be 
without  a  copy  throughout  his  pro- 
fessional career. — Pittsburg  Medical 
Review. 


GRAY  (LANDON  CARTER).  A  TREATISE  ON  NERVOUS  AND 
MENTAL  DISEASES.  For  Students  and  Practitioners  of  Medicine. 
New  (2d)  edition.  In  one  handsome  octavo  volume  of  728  pages,  with 
172  engravings  and  3  colored  plates.  Cloth,  $4.75;  leather,  $5.75. 
An  up-to-date  text-book  upon  measures  which  are  often  the  phy si- 


nervous  and  mental  diseases  com- 


bined, 
plicit, 


A  well-written,  terse,   ex- 
and    authoritative    volume 


treating  of  both  subjects  is  a  step  in 
the  direction  of  popular  demand. — 
The  Chicago  Clinical  Review. 

"The  word  treatment,"  says  the 
author,  "  has  been  construed  in  the 
broadest  sense  to  include  not  only 
medicinal  and  non-medicinal  agents, 
but  also  those  hygienic  and  dietetic 


cian's  best  reliance." — The  Journal 
of  the  American  Medical  Association. 
The  descriptions  of  the  various 
diseases  are  accurate  and  the  symp- 
toms and  differential  diagnosis  are 
set  before  the  student  in  such  a  way 
as  to  be  readily  comprehended.  The 
author's  long  experience  renders  his 
views  on  therapeutics  of  great  value. 
— The  Journal  of  Nervous  and  Men- 
tal Disease. 


12      LEA  BROTHERS  &  Co.,  PHILADELPHIA  AND  NEW  YORK. 

GREEN  (T.  HENRY).  AN  INTRODUCTION  TO  PATHOLOGY 
AND  MORBID  ANATOMY.  New  (8th)  American  from  the  eighth 
London  edition.  In  one  handsome  octavo  volume  of  582  pages,  with 
216  engravings  and  a  colored  plate.  Cloth,  $2.50,  net.  Just  ready. 


A  work  that  is  the  text-book  of 

Srobably  four-fifths  of  all  the  stu- 
ents  of  pathology  in  the   United 
States  and  Great  Britain  stands  in 
no  need  of  commendation.  The  work 
precisely  meets  the  needs  and  wishes 
of  the    general    practitioner. — The 
American  Practitioner  and  News. 
Green's  Pathology  is  the  text-book 


of  the  day — as  much  so  almost  as 
Gray's  Anatomy.  It  is  fully  up-to- 
date  in  the  record  of  fact,  and  so  pro- 
fusely illustrated  as  to  give  to  eacli 
detail  of  text  sufficient  explanation. 
The  work  is  an  essential  to  the  prac- 
titioner— whether  as  surgeon  or  phys- 
ician. It  is  the  best  of  up-to  date 
text-books. —  VirginiaMed.  Monthly. 


GREENE  (WILLIAM  H.).  A  MANUAL  OF  MEDICAL  CHEM- 
ISTRY. For  the  Use  of  Students.  Based  upon  BOWMAN'S  Medical 
Chemistry.  In  one  12mo.  vol.  of  310  pages,  with  74  illus.  Cloth,  $1.75. 

GROSS  (SAMUEL,  D.)-  A  PRACTICAL  TREATISE  ON  THE  DIS- 
EASES, INJURIES  AND  MALFORMATIONS  OF  THE  URINARY 
BLADDER,  THE  PROSTATE  GLAND  AND  THE  URETHRA. 
Third  edition.  Octavo,  574  pages,  with  170  illustrations  Cloth,  $4.50. 

GRINDON  (JOSEPH).  A  POCKET  TEXT-BOOK  OF  SKIN 
DISEASES.  In  one  handsome  12mo.  volume  of  350  pages,  with 
many  illustrations.  Shortly.  Cloth,  $1.50,  net.  Lea?*  Series  of  Pocket 
Text-looks,  edited  by  BERN  B.  GALLAUDET,  M.  D.  See  page  18. 

HABERSHON  (S.  O.).  ON  THE  DISEASES  OF  THE  ABDOMEN 
Second  American  from  the  third  English  edition.  In  one  octavo  vol- 
ume of  554  pages,  with  11  engravings.  Cloth,  $3.50. 

HALL,  (WINFIELD  S.)  TEXT-BOOK  OF  PHYSIOLOGY.  Octavo 
about  500  pages,  richly  illustrated.  In  press. 

HAMILTON  (ALLAN  MCLANE).  NERVOUS  DISEASES.  THEIR 
DESCRIPTION  AND  TREATMENT.  Second  and  revised  edition. 
In  one  octavo  volume  of  598  pages,  with  72  engravings.  Cloth,  $4. 

HARD  A  WAY  (W.  A.).    MANUAL  OF  SKIN  DISEASES.    New  (2d) 
edition.   In  one  12mo.  volume  of  560  pages,  with  40  illustrations  and 
2  plates.    Cloth,  $2.25,  net.    Just  ready. 
The  best  of  all  the  small  books  to  I  day  clinical  experience.     His  great 


recommend  to  students  and  practi- 
tioners. Probably  no  one  of  our 
dermatologists  has  had  a  wider  every- 


strength  is  in  diagnosis,  descriptions 
of  lesions  and  especially  in  treat- 
ment.— Indiana  Medical  Journal. 


HARE  (HOBART  AMORY).  PRACTICAL  DIAGNOSIS.  THE 
USE  OF  SYMPTOMS  IN  THE  DIAGNOSIS  OF  DISEASE.  New 
(4th)  edition.  In  one  octavo  volume  of  623  pages,  with  205  engravings 
and  14  full-page  colored  plates.  Cloth,  $5.00,  net.  Just  ready. 


It  is  unique  in  many  respects,  and 
the  author  has  introduced  radical 
changes  which  will  be  welcomed  by 
all.  Anyone  who  reads  this  book 
will  become  a  more  acute  observer, 
will  pay  more  attention  to  the  simple 
yet  indicative  signs  of  disease,  and  1 


he  will  become  a  better  diagnosti- 
cian. This  is  a  companion  to  Prac- 
tical Therapeutics,  by  the  same 
author,  and  it  is  difficult  to  conceive 
of  any  two  works  of  greater  practical 
utility. — Medical  Review. 


LEA  BROTHERS  &  Co.,  PHILADELPHIA  AND  NEW  YOBK.     13 

HARE  (HOBART  AMORY).  A  TEXT-BOOK  OF  PRACTICAL 
THERAPEUTICS,  with  Special  Reference  to  the  Application  of  Reme- 
dial Measures  to  Disease  and  their  Employment  upon  a  Rational 
Basis.  With  articles  on  various  subjects  by  well-known  specialists. 
Xew  (7th)  and  revised  edition.  In  one  octavo  volume  of  776  pages. 
Cloth,  $3.75,  net;  leather,  $4.50,  net. 

Its  classifications  are  inimitable,  I  it  can  be  readily  used  in  connection 
and  the  readiness  with  which  any- 1  with  Hare's  Practical  Diagnosis. 
thing  can  be  found  is  the  most  won- 1  For  the  needs  of  the  student  and 
derful  achievement  of  the  art  of  in- 1  general  practitioner  it  has  no  equal, 
dexing.  This  edition  takes  in  all  I  — Medical  Sentinel. 
the  latest  discovered  remedies. —  The  best  planned  therapeutic  work 


The  St.  Louis  Clinique. 

The  great  value  of  the  work  lies 
in  the  fact  that  precise  indications 
for  administration  are  given.  A 
complete  index  of  diseases  and 
remedies  makes  it  an  easy  reference 
work.  It  has  been  arranged  so  that 


of   the    century. — American    Prac- 
titioner and  News. 

It  is  a  book  precisely  adapted  to 
the  needs  of  the  busy  practitioner, 
who  can  rely  upon  finding  exactly 
what  he  needs. — The  National  Med- 
ical Review. 


HARE  (HOBART  AMORY)  ON  THE  MEDICAL  COMPLICA 
TIONS  AND  SEQUELJE  OF  TYPHOID  FEVER.  Octavo,  276 
pages,  21  engravings  and  two  full- page  plates.  Just  ready.  Cloth, 
$2.40,  net. 

A  very  valuable  production.    One  ,  read  with   great  profit. — Cleveland 
of  the  very   best   products  of   Dr.    Journal  of  Medicine. 
Hare  and  one  that  every  man  can  > 

HARE  (HOBART  AMORY,  EDITOR).  A  SYSTEM  OF  PRAC- 
TICAL THERAPEUTICS.  In  a  series  of  contributions  by  eminent 
practitioners.  In  four  large  octavo  volumes  comprising  about  4500 
pages,with  about  550  engravings.  Vol.  IV.,  just  ready.  For  sale  by  sub- 
scription only.  Full  prospectus  free  on  application  to  the  Publishers. 
Regular  price,  Vol.  IV.,  cloth,  $6 ;  leather,  $7 ;  half  Russia,  $8. 
Price  Vol.  IV.  to  former  or  new  subscribers  to  complete  work,  cloth, 
$5  ;  leather,  $6 ;  half  Russia,  $7.  Complete  work,  cloth,  $20 ;  leather, 
$24 ;  half  Russia,  $28. 

The  great  value  of  Hare's  System  of  Practical  Therapeutics  has  led  to  a 
widespread  demand  for  a  new  volume  to  represent  advances  in  treatment 
made  since  the  publication  of  the  first  three.  More  than  fulfilling  this 
request  the  Editor  has  secured  contributions  from  practically  a  new  corps 
of  equally  eminent  authors,  so  that  entirely  fresh  and  original  matter  is 
ensured.  The  plan  of  the  work,  which  proved  so  successful,  has  been  fol- 
lowed in  this  new  volume,  which  will  be  found  to  present  the  latest  devel- 
opments and  applications  of  this  most  practical  branch  of  the  medical  art. 
The  entire  System  is  an  unrivalled  encyclopaedia  on  the  practical  parts  of 
medicine,  and  merits  the  great  success  it  has  won  for  that  reason. 


14     LEA  BBOTHEES  &  Co.,  PHILADELPHIA  AND  NEW  YORK. 


HARTSHORNE  (HENRY).  ESSENTIALS  OF  THE  PRINCIPLES 
AND  PRACTICE  OF  MEDICINE.  Fifth  edition.  In  one  12mo. 
volume,  669  pages,  with  144  engravings.  Cloth,  $2.75 . 


—  A  HANDBOOK  OF  ANATOMY  AND  PHYSIOLOGY.    In  one 
12mo.  volume  of  310  pages,  with  220  engravings.    Cloth,  $1.75. 


A  CONSPECTUS  OF  THE  MEDICAL  SCIENCES.    Comprising 

Manuals  of  Anatomy,  Physiology,  Chemistry,  Materia  Medica,  Prac- 
tice of  Medicine,  Surgery  and  Obstetrics.  Second  edition.  In  one  royal 
12mo.  vol.  of  1028  pages,  with  477  illus.  Cloth,  $4.25 ;  leather,  $5. 

HAYDEN  (JAMES  R.).    A  MANUAL  OF  VENEREAL  DISEASES. 

New  (2d)  edition.  In  one  12mo.  volume  of  304  pages,  with  54  en- 
gravings. Cloth,  $1.50,  net.  Just  ready. 


It  is  practical,  concise,  definite 
and  of  sufficient  fulness  to  be  satis- 
factory.— Chicago  Clinical  Review. 

This  work  gives  all  of  the  prac- 
tically essential  information  about 
the  three  venereal  diseases,  gon- 
orrhoea, the  chancroid  and  syphilis. 
In  diagnosis  and  treatment  it  is  par- 


ticularly thorough,  and  may  be 
relied  upon  as  a  guide  in  the  man- 
agement of  this  class  of  diseases. — 
Northwestern  Lancet. 

It  is  well  written,  up  to  date,  and 
will  be  found  very  useful. — Inter- 
national Medical  Magazine. 


HAYEM  (GEORGES)  AND  HARE  (H.  A.).  PHYSICAL  AND 
NATURAL  THERAPEUTICS.  The  Remedial  Use  of  Heat,  Elec- 
tricity, Modifications  of  Atmospheric  Pressure,  Climates  and  Mineral 
Waters.  Edited  by  Prof.  H.  A.  HARE,  M.  D.  In  one  octavo  volume 
of  414  pages, with  113  engravings.  Cloth,  $3. 


This  well-timed  up-to-date  volume 
is  particularly  adapted  to  the  re- 
quirements of  the  general  practi- 
tioner. The  section  on  mineral 
waters  is  most  scientific  and  prac- 
tical. Some  200  pages  are  given  up 
to  electricity  and  evidently  embody 
the  latest  scientific  information  on 
the  subject.  Altogether  this  work 
is  the  clearest  and  most  practical  aid 
to  the  study  of  nature's  therapeutics 
that  has  yet  come  under  our  obser- 
vation.— The  Medical  Fortnightly. 

For  many  diseases  the  most  potent 
remedies  lie  outside  of  the  materia 
medica,  a  fact  yearly  receiving  wider 


recognition.  Within  this  large 
range  of  applicability,  physical 
agencies  when  compared  with  drugs 
are  more  direct  and  simple  in  their 
results.  Medical  literature  has  long 
been  rich  in  treatises  upon  medical 
agents,  but  an  authoritative  work 
upon  the  other  great  branch  of 
therapeutics  has  until  now  been  a 
desideratum.  The  section  on  climate, 
rewritten  by  Prof.  Hare,  will,  for 
the  first  time,  place  the  abundant 
resources  of  our  country  at  the  in- 
telligent command  of  American 
practitioners.  —  The  Kansas  City 
Medical  Index. 


HERMAN  (G.  ERNEST).    FIRST  LINES  IN  MIDWIFERY. 

one  12mo.  vol.  of  198  pages,  with  80  engravings.     Cloth,  $1.25. 
Student's  Series  of  Manuals,  page  27. 


In 


HERMANN  (L.).  EXPERIMENTAL  PHARMACOLOGY.  A  Hand- 
book of  the  Methods  for  Determining  the  Physiological  Actions  of 
Drugs.  Translated  by  ROBERT  MEADE  SMITH,  M.  D.  In  one  J2mo, 
volume  of  199  pages,  with  33  engravings,  Cloth,  $J,5Q, 


LEA  BROTHERS  &  Co.,  PHILADELPHIA  AND  NEW  YORK.     15 


HERRICK  (JAMES  B.).  A  HANDBOOK  OF  DIAGNOSIS.  In 
one  handsome  12mo.  volume  of  429  pages,  with  80  engravings  and  2 
colored  plates.  Cloth,  $2.50. 


Excellently  arranged,  practical, 
concise,  up-to-date,  and  eminently 
well  fitted  lor  the  use  of  the  prac- 
titioner as  well  as  of  the  student— 
Chicago  Med.  Recorder. 

This  volume  accomplishes  its  ob- 
jects more  thoroughly  and  com- 
pletely than  any  similar  work  yet 
published.  Each  section  devoted"  to 
diseases  of  special  systems  is  pre- 
ceded with  an  exposition  of  the 
methods  of  physical,  chemical  and 


microscopical  examination  to  be  em- 
ployed in  each  class.  The  technique 
of  blood  examination,including  color 
analysis,  is  very  clearly  stated. 
Uranalysis  receives  adequate  space 
and  care. — New  York  Med.  Journal. 
We  commend  the  book  not  only  to 
the  undergraduate,  but  also  to  the 
physician  who  desires  a  ready  means 
of  refreshing  his  knowledge  of  diag- 
nosis in  the  exigencies  of  professional 
life. — Memphis  Medical  Monthly. 


HILJj  (BERKELEY).  SYPHILIS  AND  LOCAL  CONTAGIOUS 
DISORDERS.  In  one  8vo.  volume  of  479  pages.  Cloth,  $3.25. 

HLLLIER  (THOMAS).  A  HANDBOOK  OF  SKIN  DISEASES. 
Second  edition.  In  one  royal  12mo.  volume  of  353  pages,  with  two 
plates.  Cloth,  $2.25. 

HIRST  (BARTON  C.)  AND  PD3RSOL  (GEORGE  A.).  HUMAN 

MONSTROSITIES.  Magnificent  folio,  containing  220  pages  of  text 
and  illustrated  with  123  engravings  and  39  large  photographic  plates 
from  nature.  In  four  parts,  price  each,  $5.  Limited  edition.  For  sale 
by  subscription  only. 

HOBLYN  (RICHARD  D.).  A  DICTIONARY  OF  THE  TERMS 
USED  IN  MEDICINE  AND  THE  COLLATERAL  SCIENCES. 
In  one  12mo.  volume  of  520  double-columned  pages.  Cloth,  $1.50 ; 
leather,  $2. 

HODGE  (HUGH  Li.).  ON  DISEASES  PECULIAR  TO  WOMEN. 
INCLUDING  DISPLACEMENTS  OF  THE  UTERUS.  Second  and 
revised  edition.  In  one  8vo.  vol.  of  519  pp.,  with  illus.  Cloth,  $4.50. 

HOFFMANN  (FREDERICK)  AND  POWER  (FREDERICK  B.). 

A  MANUAL  OF  CHEMICAL  ANALYSIS,  as  Applied  to  the 
Examination  of  Medicinal  Chemicals  and  their  Preparations.  Third 
edition,  entirely  rewritten  and  much  enlarged.  In  one  handsome  octavo 
volume  of  621  pages,  with  179  engravings.  Cloth,  $4.25. 

HOLMES  (TIMOTHY).  A  TREATISE  ON  SURGERY.  Its  Prin- 
ciples and  Practice.  A  new  American  from  the  fifth  English  edition. 
Edited  by  T.  PICKERING  PICK,  F.R.C.S.  In  one  handsome  octavo  vol- 
ume of  1008  pages,  with  428  engravings.  Cloth,  $6 ;  leather,  $7. 


—  A  SYSTEM  OF  SURGERY.  With  notes  and  additions  by  various 
American  authors.  Edited  by  JOHN  H.  PACKARD,  M.  D.  In  three 
very  handsome  8vo.  volumes  containing  3137  double-columned  pages, 
with  979  engravings  and  13  lithographic  plates.  Per  volume,  cloth,  $6 ; 
leather,  $7 ;  fcalf  Russia,  $7.5Q,  For  tv4t  by  tubwriptivn  only. 


16     LEA  BROTHEBS  &  Co.,  PHILADELPHIA  AND  NEW  YORK. 


HORNER  (WILLIAM  E.).  SPECIAL  ANATOMY  AND  HIS- 
TOLOGY. Eighth  edition,  revised  and  modified.  In  two  large  8vo. 
volumes  of  1007  pages,  containing  320  engravings.  Cloth,  $6. 


HUDSON  (A.).  LECTURES  ON  THE  STUDY  OF  FEVER.    In  one 
octavo  volume  of  308  pages.    Cloth,  $2.50. 


HUTCHISON  (ROBERT)  AND  RAINY  (HARRY).  CLINICAL 
METHODS.  A  GUIDE  TO  THE  PRACTICAL  STUDY  OF 
MEDICINE.  In  one  12mo.  volume  of  562  pages,  with  137  engrav- 
ings and  8  colored  plates.  Cloth,  $3.00. 


A  comprehensive,  clear  and  re- 
markably up-to-date  guide  to  clinical 
diagnosis.  The  illustrations  are 
plentiful  and  excellent.  As  exam- 
ples of  the  more  recent  additions  to 


medical  knowledge  which  receive 
recognition,  we  mention  Widal's 
test  for  typhoid  and  the  Neuron 
theory  of  the  nervous  system. — 
Montreal  Medical  Journal. 


HUTCHINSON  (JONATHAN).  SYPHILIS.  In  one  pocket-size  12mo. 
volume  of  542  pages,  with  8  chromo-lithographic  plates.  Cloth,  $2.25. 
See  Series  of  Clinical  Manuals,  p.  25. 


HYDE  (JAMES  NEVINS).  A  PRACTICAL  TREATISE  ON  DIS- 
EASES OF  THE  SKIN.  New  (4th)  edition,  thoroughly  revised. 
In  one  octavo  volume  of  815  pages,  with  110  engravings  and  12  full- 
page  plates,  4  of  which  are  colored.  Cloth,  $5.25 ;  leather,  $6.25. 


This  edition  has  been  carefully  re- 
vised, and  every  real  advance  has 
been  recog  n  i  zed .  Theworkanswers 
the  needs  of  the  general  practitioner, 
the  specialist,  and  the  student.— The 
Ohio  Med.  Jour. 

A  treatise  of  exceptional  merit 
characterized  by  conscientious  care 
and  scientific  accuracy.  —  Buffalo 
Med.  Journal. 

A  complete  exposition  of  our 
knowledge  of  cutaneous  medicine  as 
it  exists  to-day.  The  teaching  in- 
culcated throughout  is  sound  as  well 


as  practical. — The  American  Jour- 
nal of  the  Medical  Sciences. 

It  is  the  best  one-volume  work 
that  we  know.  The  student  who 
gets  this  book  will  find  it  a  useful 
investment,  as  it  will  well  serve  him 
when  he  goes  into  practice. —  Vir- 
ginia Medical  Semi-Monthly. 

A  full  and  thoroughly  modern 
text-book  on  dermatology.  —  The 
Pittsburg  Medical  Review. 

It  is  the  most  practical  hand- 
book on  dermatology  with  which  we 
are  acquainted. — The  Chicago  Med- 
ical Recorder. 


JACKSON  (GEORGE  THOMAS).  THE  READY-REFERENCE 
HANDBOOK  OF  DISEASES  OF  THE  SKIN.  New  (3d)  edition. 
In  one  12mo.  volume  of  637  pages,  with  75  illustrations  and  a  colored 
plate.  Just  ready.  Cloth,  $2.50,  net. 


As  a  student's  manual,  it  may  be 
considered  beyond  criticism.  The 
book  is  singularly  full.—  St.  Louis 
Medical  and  Surgical  Journal. 


Without  doubt  forms  one  of  the 
best  guides  for  the  beginner  in  der- 
matology that  is  to  be  found  in  the 
English  language. — Medicine. 


JAMIESON,(W.  AJLL.AN).  DISEASES  OF  THE  SKIN.  Third 
edition.  In  one  octavo  volume  of  656  pages,  with  1  engraving  and  9 
double-page  chromo-lithographic  plates,  Cloth,  $6, 


LEA  BROTHERS  &  Co.,  PHILADELPHIA  AND  NEW  YORK.  17 

JEWETT  (CHARLES).  ESSENTIALS  OF  OBSTETRICS.    In  one 
12mo.  volume  of  356  pages,  with  80  engravings  and  3  colored  plates. 
Cloth,  $2.25.    Just  ready. 
An  exceedingly  useful  manual  for  j  ing  it  in  attractive  and  easily  tangi- 

student  and  practitioner.    The  au-  j  ble  form.    The  book  is  well  illus- 

thor  has  succeeded  unusually  well  j  trated  throughout. — Nashville  Jour. 

in  condensing  the  text  and  in  arrang- 1  of  Medicine  and  Surgery. 

THE  PRACTICE  OF  OBSTETRICS.     By   American    Authors. 

One  large  octavo  volume  of  763  pages,  with  441  engravings  in  black 
and  colors,  and  22  full-page  colored  plates.  Just  ready.  Cloth, 
$5.00,  net ;  leather,  $6.00,  net. 

A  clear  and  practical  treatise  upon  I  the  book  abounds.  The  work  is 
obstetrics  by  well-known  teachers  of  i  sure  to  be  popular  with  medical 
the  subject.  A  special  feature  of !  students,  as  well  as  being  of  extreme 
this  work  would  seem  to  be  the  i  value  to  the  practitioner.  —  The 
excellent  illustrations  with  which  |  Medical  Age. 

JONES  (C.  HANDF1ELD).  CLINICAL  OBSERVATIONS  ON 
FUNCTIONAL  NERVOUS  DISORDERS.  Second  American  edi- 
tion. In  one  octavo  volume  of  340  pages.  Cloth,  $3.25. 

JUL.ER  (HENRY).  A  HANDBOOK  OF  OPHTHALMIC  SCIENCE 
AND  PRACTICE.  Second  edition.  In  one  octavo  volume  of  549 
pages,  with  201  engravings,  17  chromo-lithographic  plates,  test-types  of 
Jaeger  and  Snellen,  and  Holmgren's  Color-Blindness  Test.  Cloth, 
$5.50;  leather,  $6.50. 

The  volume  is  particularly  rich  in  |  color  blindness,   etc.    The   sections 
matter  of  practical  value,  such  as  '  devoted  to  treatment  are  singularly 
directions   for    diagnosing,    use    of   full  and  concise. — Medical  Age. 
instruments,  testing  for  glasses,  for  | 

KING  (A.  F.  A.).  A  MANUAL  OF  OBSTETRICS.  Seventh  edition. 
In  one  12mo.  volume  of  573  pages,  with  223  illustrations.  Cloth, 
$2.50. 

From  first  to  finish  it  is  thoroughly  cyclopedias.  The  well-arranged 
practical,  concise  in  expression,  well  index  renders  the  book  useful  to 
illustrated,  and  includes  a  statement !  the  practitioner  who  is  in  haste  to 
of  nearly  every  fact  of  importance  refresh  his  memory.  —  Virginia 
discussed  in  obstetric  treatises  or  |  Medical  Semi-Monthly. 

KIRK  (EDWARD  C.).  OPERATIVE  DENTISTRY.  Handsome 
octavo  of  700  pages,  with  751  illustrations.  Just  ready.  See  American 
Text- Books  of  Dentistry,  page  2. 

We  have  only  the  highest  praise    tempted.     We  can  heartily  recom- 
for  this  valuable  work.   It  is  replete  ;  mend    it    to    the    profession. — The 
in  every  particular,  and  surpasses    Ohio  Dental  Journal. 
anything  of  the  kind  heretofore  at- ) 

KLEIN  (E.).  ELEMENTS  OF  HISTOLOGY.  New  (5th)  edition.  In 
one  12mo.  volume  of  506  pages,  with  296  engravings.  Just  ready. 
Cloth,  $2.00,  net.  See  Student's  Series  of  Manuals,  page  27. 

It  is  the  most  complete  and  con-       This  work  deservedly  occupies  a 
cise  work  of  the  kind  that  has  yet   first  place  as  a  text-book  on  his- 
emanated  from  the  press. — ThcMed-  \  tology. — Canadian  Practitioner, 
ical  Age. 


18     LEA  BROTHERS  &  Co.,  PHILADELPHIA  AND  NEW  YORK. 

LANDIS  (HENRY  G.).  THE  MANAGEMENT  OF  LABOR.  In  one 

handsome  12mo.  volume  of  329  pages,  with  28  illus.   Cloth,  $1.75. 

LA  ROCHE  (R.).  YELLOW  FEVER.  In  two  8vo.  volumes  of  1468 
pages.  Cloth,  $7. 

LAURENCE  (J.  Z.)  AND  MOON  (ROBERT  C.).  A  HANDY- 
BOOK  OF  OPHTHALMIC  SURGERY.  Second  edition.  In  one 
octavo  volume  of  227  pages,  with  66  engravings.  Cloth,  $2.75. 

LEA'S  SERIES  OF  POCKET  TEXT-BOOKS,  edited  by  BERN 
B.  GALLATJDET,  M.  D.  Covering  the  entire  field  of  Medicine  in  a 
series  of  16  very  handsome  cloth-bound  12mo.  volumes  of  350-450 
pages  each,  profusely  illustrated.  Compendious,  clear,  trustworthy  and 
modern,  and  issued  at  the  very  moderate  price  of  $1.50,  net,  per 
volume.  The  following  volumes  constitute  the  series. 

COATES'  Bacteriology  and  Hygiene.  BROCKWAY'S  Anatomy.  COLLINS 
and  ROCKWELL'S  Physiology.  MARTIN  and  ROCKWELL'S  Chemistry 
and  Physics.  NICHOLS  and  VALE'S  Histology  and  Pathology. 
SCHLEIF'S  Materia  Medica,  Therapeutics,  Medical  Latin,  etc.  MALS- 
BARY'S  Practice  of  Medicine.  COLLINS'  Diagnosis.  POTTS'  Nervous 
and  Mental  Diseases.  GALLAUDET'S  Surgery.  LIKES'  Genito- 
Urinary  and  Venereal  Diseases.  GRINDON'S  Dermatology.  BALLEN- 
GER  and  WIPPERN'S  Diseases  of  the  Eye,  Ear,  Throat  and  Nose. 
EVANS'  Obstetrics.  CROCKETT'S  Gynecology.  TUTTLE'S  Diseases  of 
Children. 

For  separate  notices  see  under  various  authors'  names. 

LEA  (HENRY  C.).  A  HISTORY  OF  AURICULAR  CONFESSION 
AND  INDULGENCES  IN  THE  LATIN  CHURCH.  In  three 
octavo  volumes  of  about  500  pages  each.  Per  volume,  cloth,  $3.00. 

CHAPTERS  FROM  THE  RELIGIOUS  HISTORY  OF  SPAIN; 

CENSORSHIP  OF  THE  PRESS;  MYSTICS  AND  ILLUMINATI- 
THE  ENDEMONIADAS;  EL  SANTO  NINO  DE  LA  GUARDIA; 
BRIANDA  DE  BARDAXI.  12mo.,  522  pages.  Cloth,  $2.50. 

FORMULARY  OF  THE   PAPAL  PENITENTIARY.    In  one 

octavo  volume  of  221  pages,  with  frontispiece.    Cloth,  $2.50. 

SUPERSTITION  AND  FORCE;  ESSAYS  ON  THE  WAGER 

OF  LAW,  THE  WAGER  OF  BATTLE,  THE  ORDEAL  AND 
TORTURE.  Fourth  edition,  thoroughly  revised.  In  one  hand- 
some royal  12mo.  volume  of  629  pages.  Cloth,  $2.75. 

STUDIES  IN  CHURCH  HISTORY.    The  Rise  of  the  Temporal 

Power — Benefit  of  Clergy — Excommunication.  New  edition.  In  one 
handsome  12mo.  volume  of  605  pages.  Cloth,  $2.50. 


AN  HISTORICAL  SKETCH  OF  SACERDOTAL  CELIBACY 

IN  THE  CHRISTIAN  CHURCH.    Second  edition.    In  one  hand- 
some octavo  volume  of  685  pages.    Cloth,  $4.50. 

LEHMANN  (C.  G.).    A  MANUAL  OF  CHEMICAL  PHYSIOLOGY. 
Jn  one  8vo.  volume  of  327  pages,  with  41  engravings.     Cloth,  $2,25. 


BROTHERS  &  Co.,  PHILADELPHIA  AND  NEW  YORK.     19 


LIKES  (SYLVAN  H.).  A  POCKET  TEXT-BOOK  OF  GENITO- 
URINARY AND  VENEREAL  DISEASES.  In  one  handsome 
12mo.  volume  of  about  350  pages,  with  many  illustrations.  Shortly. 
Cloth,  $1.50,  net.  Lea's  Series  of  Pocket  Text-booh,  edited  by  BERN 
B.  GALLAUDET,  M.  D.  See  page  18. 

LOOMIS  (ALFRED  L.)  AND  THOMPSON  (W.  OILMAN, 
EDITORS).  A  SYSTEM  OF  PRACTICAL  MEDICINE.  In 

Contributions  by  Various  American  Authors.  In  four  very  hand- 
some octavo  volumes  of  about  900  pages  each,  fully  illustrated  in 
in  black  and  colors.  Complete  work  now  ready-  Per  volume,  cloth, 
$5 ;  leather,  $6 ;  half  Morocco,  $7.  For  sale  by  subscription  only. 
Full  prospectus  free  on  application  to  the  Publishers.  See  American 
System  of  Practical  Medicine,  page  2. 


LUFF  (ARTHUR  P.).  MANUAL  OF  CHEMISTRY,  for  the  use  of 
Students  of  Medicine.  In  one  12mo.  volume  of  522  pages,  with  36 
engravings.  Cloth,  $2.  See  Student's  Series  of  Manuals,  page  27. 


LYMAN  (HENRY  M.).    THE  PRACTICE  OF  MEDICINE.    In  one 

very  handsome  octavo  volume  of  925  pages,  with  170  engravings. 
Cloth,  $4.75 ;  leather,  $5.75. 

Complete,  concise,  fully  abreast  of  Practical,  systematic,  complete  and 

the  times  and  needed  by  all  students  well  balanced. — Chicago  Med.  Re- 

and  practitioners. —  Univ.  Med.  Mag.  carder. 

An  exceedingly  valuable  text-book. 


LYONS  (ROBERT  D.).    A  TREATISE  ON  FEVER. 
volume  of  362  pages.    Cloth,  $2.25. 


In  one  octavo 


MACKENZIE  (JOHN  NOLAND).  ON  THE  NOSE  AND  THROAT. 

Handsome  octavo,  about  600  pages,  richly  illustrated.     Preparing. 


MAISCH  (JOHN  M.).  A  MANUAL  OF  ORGANIC  MATERIA 
MEDICA.  New  (7th)  edition,  thoroughly  revised  by  H.  C.  C.  MAISCH, 
Ph.  G.,  Ph.  D.  In  one  very  handsome  12mo.  volume  of  512  pages,  with 
285  engravings.  Just  ready.  Cloth,  $2.50,  net. 


Used  as  text-book  in  every  college 
of  pharmacy  in  the  United  States 
and  recommended  in  medical  col- 
leges.— American  Therapist. 

Noted  on  both  sides  of  the  Atlantic 
and  esteemed  as  much  in  Germany  as 


in  America.  The  work  has  no  equal. 
— Dominion  Med.  Monthly. 

The  best  handbook  upon  phar- 
macognosy  of  any  published  in  this 
country. — Boston  Med.  &  Sur.  Jonr. 


20    LEA  BROTHERS  &  Co.,  PHILADELPHIA  AND  NEW  YORK. 

MALSBARY  (GEORGE  E.).  A  POCKET  TEXT-BOOK  OF 
THEORY  AND  PRACTICE  OF  MEDICINE.  In  one  handsome 
12mo.  volume  of  about  350  pages.  Cloth,  $1.50,  net.  Shortly.  Lea's 
Series  of  Pocket  Text-books,  edited  by  BERN  B.  GALLAUDET,  M.  D. 
See  page  18. 

MANUALS.  See  Student's  Quiz  Series,  page  27,  Student's  Series  of 
Manuals,  page  27,  and  Series  of  Clinical  Manuals,  page  25. 

MARSH  (HOWARD).  DISEASES  OF  THE  JOINTS.  In  one  12mo. 
volume  of  468  pages,  with  64  engravings  and  a  colored  plate.  Cloth,  $2. 
See  Series  of  Clinical  Manuals,  page  25. 

MARTIN  (EDWARD).  A  MANUAL  OF  SURGICAL  DIAGNOSIS. 
In  one  12mo.  volume  of  about  400  pp.,  fully  illustrated.  Preparing. 

MARTIN  (WALTON)  AND  ROCKWELL  (WM.  H.).  A  POCKET 
TEXT-BOOK  OF  CHEMISTRY  AND  PHYSICS.  In  one  hand- 
some 12mo.  volume  of  about  350  pages,  with  many  illustrations.  Cloth, 
$1.50,  net.  Shortly.  Lea's  Series  of  Pocket  Text-books,  edited  by 
BERN  B.  GALLAUDET,  M.  D.  See  page  18. 

MAY  (C.  H.).  MANUAL  OF  THE  DISEASES  OF  WOMEN.  For 
the  use  of  Students  and  Practitioners.  Second  edition,  revised  by  L. 
S.  RATJ,  M.  D.  In  one  12mo.  volume  of  360  pages,  with  31  engrav- 
ings. Cloth,  $1.75. 

MEDICALi  NEWS  POCKET  FORMULARY,  see  page  32. 

MITCHELL.  (S.  WEIR).  CLINICAL  LESSONS  ON  NERVOUS 
DISEASES.  In  one  12mo.  volume  of  299  pages,  with  19  engravings 
and  2  colored  plates.  Cloth,  $2.50.  Of  the  hundred  numbered  copies 
with  the  Author's  signed  title  page  a  few  remain ;  these  are  offered 
in  green  cloth,  gilt  top,  at  $3.50,  net. 


The  book  treats  of  hysteria,  recur- 
rent melancholia,  disorders  of  sleep, 
choreic  movements,  false  sensations 
of  cold,  ataxia,  hemiplegic  pain, 
treatment  of  sciatica,  erythromelal- 
gia,  reflex  ocularneurosis,  hysteric 


contractions,  rotary  movements  in 
the  feeble  minded,  etc.  Few  can 
speak  with  more  authority  than  the 
author. —  The  Journal  of  the  Ameri- 
can Medical  Association. 


MITCHELL  (JOHN  K.).  REMOTE  CONSEQUENCES  OF  IN- 
JURIES OF  NERVES  AND  THEIR  TREATMENT.  In  one 
handsome  12mo.  volume  of  239  pages, with  12  illustrations.  Cloth,  $1.75. 


Injuries  of  the  nerves  are  of  fre- 
quent occurrence  in  private  practice, 
and  often  the  cause  of  intractable 
and  painful  conditions,  conse- 
quently this  volume  is  of  especial 
interest.  Doctor  Mitchell  has  had 


access  to  hospital  records  for  the  last 
thirty  years,  as  well  as  to  the 
government  documents,  and  has 
skilfully  utilized  his  opportunities. 
— The  Med.  Age. 


MORRIS  (MALCOLM).  DISEASES  OF  THE  SKIN.  New  (2d) 
edition.  In  one  12mo.  volume  of  601  pages,  with  10  chromo-litho- 
graphic  plates  and  26  engravings.  Cloth,  $3.25,  net.  Just  ready. 


MULLER  (J.).    PRINCIPLES  OF   PHYSICS   AND  METEOROL- 
OGY.   In  one  large  8vo.  vol.  of  623  pages,  with  638  cuts.  Cloth,  $4.50. 


IB 

Magazine. 

His  descriptions  of  the  diagnostic 
manifestations  of  diseases  are  accu- 
rate. This  work  will  meet  all  the 
requirements  of  student  and  physi- 
cian.— The  Medical  News. 

From  its  pages  may  be  made  the 
diagnosis  of  every  malady  that 
afflicts  the  human  body,  including 
those  which  in  general  are  dealt 
with  only  by  the  specialist.— North- 
western Lancet. 


LEA  BROTHEBS  A  Co.,  PHILADELPHIA  AND  NEW  YORK.     21 

MUSSER  (JOHN  H.).   A  PRACTICAL  TREATISE  ON  MEDICAL 
DIAGNOSIS,  for  Students  and  Physicians.    New  (3d)  edition,  thor- 
oughly revised.    In  one  octavo  volume  of  about  1000  pages,  with  about 
220  engravings  and  48  full-page  colored  plates.    In  press. 
Notices  of  previous  edition  are  appended. 

We  have  no  work  of  equal  value  i     It  so  thoroughly  meets  the  precise 
English. —  University    Medical   demands  incident  to  modern  research 

that  it  has  been  adopted  as  a  leading 
text-book  by  the  medical  colleges 
of  this  country. — North  American 
Practitioner. 

Occupies  the  foremost  place  as  a 
thorough,  systematic  treatise.— Ohio 
Medical  Journal. 

The  best  of  its  kind,  invaluable  to 
the  student,  general  practitioner  and 
teacher. — Montreal  Medical  Journa  I. 


NATIONAL*  DISPENSATORY.  See  Stille,  Maisch  &  Caspari,  p.  27. 

NATIONAL  FORMULARY.  See  Stille,  Maisch  &  Caspari' s  National 
Dispensatory,  page  27. 

NATIONAL  MEDICAL  DICTIONARY.    See  Billings,  page  4. 

NETTLESHIP  (E.).  DISEASES  OF  THE  EYE.  New  (5th)  American 
from  sixth  English  edition,  thoroughly  revised.  In  one  12mo.  volume 
of  521  pages,  with  161  engravings,  and  2  colored  plates,  test-types, 
formulae  and  color-blindness  test.  Cloth,  $2.25.  Just  ready. 

By  far  the  best  student's  text-book  English     language.  —  Journal      of 
on  the  subject  of  ophthalmology  and  !  Medicine  and  Science. 
is  conveniently  and    concisely   ar-  j     The  present  edition  is  the  result 
ranged. — The  Clinical  Review.  of  revision  both  in    England  and 

It  has  been  conceded  by  ophthal-  j  America,  and  therefore  contains  the 
mologists  generally  that  this  work  latest    and    best    ophthalmological 


for    compactness,    practicality   and  ideas  of  both  continents. — The  Phy~ 
rness    has  no  superior    in  the  ;  sician  and  Surgeon. 


clearness 


NICHOLS  (JOHN  B.)  AND  VALE  (F.  P.).  A  POCKET  TEXT- 
BOOK OF  HISTOLOGY  AND  PATHOLOGY.  In  one  handsome 
I2mo.  volume  of  about  350  pages,  with  many  illustrations.  In  press. 
Cloth,  $1.50,  net.  Lea's  Series  of  Pocket,  Text-books,  edited  by  BERN 
B.  GALLAUDET,  M.  D.  See  page  18. 

NORRIS  (WM.  F.)  AND  OLIVER  (CHAS.  A.).  TEXT-BOOK  OF 
OPHTHALMOLOGY.  In  one  octavo  volume  of  641  pages,  with  357 
engravings  and  5  colored  plates.  Cloth,  $5 ;  leather,  $6. 

A  safe  and  admirable  guide,  well  best,  the  safest  and  the  most  conir re- 
qualified  to  furnish  a  working  !  hensive  volume  upon  the  subject  that 
knowledge  of  ophthalmology.  —  has  ever  been  offered  to  the  Ainer- 


Johns  Hopkins  Hospital  Bulletin. 

It   is  practical  in   its  teachings. 
We  unreservedly  endorse  it  as  the 


ican    medical    public. — Annals    of 
Ophthalmology  and  Otology. 


22     LEA  BROTHERS  &  Co.,  PHILADELPHIA  AND  NEW  YORK. 

OWEN    (EDMUND).      SURGICAL    DISEASES    OF    CHILDREN. 

In  one  12mo.  volume  of  525  pages,  with  85  engravings  and  4  colored 
plates.    Cloth,  $2.    See  Series  of  Clinical  Manuals,  page  25. 


PARK  (ROSWELL,).  A  TREATISE  ON  SURGERY  BY  AMERI- 
CAN AUTHORS.  New  and  condensed  edition.  In  press.  In  one 
royal  octavo  volume  of  about  1250  pages,  with  about  1000  engravings 
and  many  full-page  plates.  ^g^-This  work  is  also  published  in  a 
larger  edition,  comprising  two  volumes.  Volume  I.,  General  Surgery, 
799  pages,  with  356  engravings  and  21  full-page  plates,  in  colors  and 
monochrome.  Volume  II.,  Special  Surgery,  800  pages,  with  430  engra- 
vings and  17  full-page  plates,  in  colors  and  monochrome.  Per  volume, 
cloth,  $4.50 ;  leather,  $5.50.  Net. 

The  work  is  fresh,  clear  and  practi- 1  way  that  they  add  great  force  to  the 
cal,  covering  the  ground  thoroughly  text.— The  Chicago  Medical  Ee- 
yet  briefly,  and  well  arranged  for  corder. 

rapid  reference,  so  that  it  will  be  of j  The  various  writers  have  em- 
special  value  to  the  student  and  busy  j  bodied  the  teachings  accepted  at 
practitioner.  The  pathology  is  !  the  present  hour.— The  Nort h  Amer- 
broad,  clear  and  scientific,  while  the  !  ican  Practitioner. 
suggestions  upon  treatment  are  Both  for  the  student  and  practi- 
clear-cut,  thoroughly  modern  and  I  tioner  it  is  most  valuable.  It  is 
admirably  resourceful.— Johns  Hop-  thoroughly  practical  and  yet  thor- 
kins  Hospital  Bulletin.  \  oughly  scientific. — Medical  News. 

The  latest  and  best  work  written  j  A  truly  modern  surgery,  not  only 
upon  the  science  and  art  of  surgery.  •  in  pathology,  but  also  in  sound 
Columbus  Medical  Journal.  surgical  therapeutics.  —  New  Or- 

The  illustrations  are  almost  en-  !  leans  Med.  and  Surgical  Journal. 
tirely  new  and  executed  in  such  a 


PARK  (WILLIAM  H.).  BACTERIOLOGY  IN  MEDICINE  AND 
SURGERY.  12mo.,  about  550  pages,  fully  illustrated.  In  press. 

PARRY  (JOHN  S.).  EXTRA-UTERINE  PREGNANCY,  ITS 
CLINICAL  HISTORY,  DIAGNOSIS,  PROGNOSIS  AND  TREAT- 
MENT. In  one  octavo  volume  of  272  pages.  Cloth,  $2.50. 


PARVIN  (THEOPHELUS).  THE  SCIENCE  AND  ART  OF  OB- 
STETRICS. Third  edition.  In  one  handsome  octavo  volume  of 
677  pages,  with  267  engravings  and  2  colored  plates.  Cloth,  $4.25  ; 
leather,  $5.25. 


In  the  foremost  rank  among  the 
most  practical  and  scientific  medical 
works  of  the  day. — Medical  News. 

It  ranks  second  to  none  in  the 
English  language. — Annals  of  Gyne- 
cology  and  Pediatry. 

The  book  is  complete  in  every  de- 
partment, and  contains  all  the  neces- 
sary detail  required  by  the  modern 


practising  obstetrician.  —  Interna- 
tional Medical  Magazine. 

Parvin's  work  is  practical,  con- 
cise and  comprehensive.  We  com- 
mend it  as  first  of  its  class  in  the 
English  language. — Medical  Fort- 
nightly. 

It  is  an  admirable  text-book  in 
every  sense  of  the  word. — Nashville 
Journal  of  Medicine  and  Surgery. 


LEA  BBOTHEKS  &  Co.,  PHILADELPHIA  AND  NEW  YORK.     23 

PEPPER'S  SYSTEM  OF  MEDICINE.    See  page  3. 

PEPPER  (A.  J.).  FORENSIC  MEDICINE.  In  press.  See  Student's 
Series  of  Manuals,  page  27. 

SURGICAL  PATHOLOGY.    In  one  12mo.  volume  of  511  pages, 

with  81  engravings.   Cloth,  $2.   See  Student's  Series  of  Manuals,  p.  27. 

PICK  (T.  PICKERING).  FRACTURES  AND  DISLOCATIONS. 
In  one  12mo.  volume  of  530  pages,  with  93  engravings.  Cloth,  $2. 
See  Series  of  Clinical  Manuals,  page  25. 

PLAYFAIR  (W.  8.).  A  TREATISE  ON  THE  SCIENCE  AND 
PRACTICE  OF  MIDWIFERY.  Seventh  American  from  the  ninth 
English  edition.  In  one  octavo  volume  of  700  pages,  with  207 
engravings  and  7  plates.  Cloth,  $3.75  net ;  leather,  $4.75,  net.  Just 
ready. 

In  the  numerous  editions  which   obstetrician.    It  holds  a  place  among 
have  appeared  it  has  been  kept  con-    the  ablest  English-speaking  authori- 


stantly  in  the  foremost  rank.  It  is 
a  work  which  can  be  conscientiously 
recommended  to  the  profession. — 
The  Albany  Medical  Annals. 

This  work  must  occupy  a  fore- 
most place  in  obstetric  medicine  as 
a  safe  guide  to  both  student  and 


ties  on  the  obstetric    art. — Buffalo 
Medical  and  Surgical  Journal. 

An  epitome  of  the  science  and 
practice  of  midwifery,  which  em- 
bodies all  recent  advances.  —  The 
Medical  Fortnightly. 


THE  SYSTEMATIC  TREATMENT  OF  NERVE  PROSTRA- 
TION AND  HYSTERIA.  In  one  12mo.  volume  of  97  pages. 
Cloth,  $1. 

POCKET  FORMULARY,  see  page  32. 
POCKET  TEXT-BOOKS,  see  page  18. 

POLJTZER  (ADAM).  A  TEXT-BOOK  OF  THE  DISEASES  OF  THE 
EAR  AND  ADJACENT  ORGANS.  Second  American  from  the 
third  German  edition.  Translated  by  OSCAR  DODD,  M.  D.,  and 
edited  by  SIB  WILLIAM  DALBY,  F.  R.  C.  S.  In  one  octavo  volume  of 
748  pages,  with  330  original  engravings.  Cloth,  $5.50. 

The  anatomy  and  physiology  of  ment  are  clear  and  reliable.  We 
each  part  of  the  organ  of  hearing  can  confidently  recommend  it,  for  it 
are  carefully  considered,  and  then  contains  all  that  is  known  upon  the 
follows  an  enumeration  of  the  dis-  subject. — London  Lancet. 
eases  to  which  that  special  part  of  A  safe  and  elaborate  guide  into 
the  auditory  apparatus  is  especially  every  part  of  otology. — American 
liable.  The  indications  for  treat-  Journal  of  the  Medical  Sciences. 

POTTS  (CHARLES  S.).  A  POCKET  TEXT-BOOK  OF  NERVOUS 
AND  MENTAL  DISEASES.  In  one  handsome  12mo.  volume  of 
about  450  pages.  Cloth,  £1. 50,  net.  Shortly.  Lea's  Series  of  Pocket 
Text-books,  edited  by  BERN  B.  GALLAUDET,  M.  D.  See  page  18. 

PROGRESSIVE  MEDICINE,  see  page  32. 

PURDY  (CHARLES  WA  BRIGHT'S  DISEASE  AND  ALLIED 
AFFECTIONS  OF  THE  KIDNEY.  In  one  octavo  volume  of  288 
pages,  with  18  engravings.  Cloth,  $2. 


24    LEA  BROTHERS  &  Co.,  PHILADELPHIA  AND  NEW  YORK. 

PYE-SMITH  (PHELBP  H.).  DISEASES  OF  THE  SKIN.  In  one 
12mo.  vol.  of  407  pp.,  with  28  illus.,  18  of  which  are  colored.  Cloth,  $2. 

QUIZ  SERIES.    See  Student's  Quiz  Series,  page  27. 

RALFE    (CHARLES  H.).      CLINICAL     CHEMISTRY.     In    one 

12mo.  volume  of  314  pages,  with  16  engravings.    Cloth,  $1.50.    See 
•    Student's  Series  of  Manuals,  page  27. 

RAMSBOTHAM  (FRANCIS  H.).  THE  PRINCIPLES  AND  PRAC- 
TICE OF  OBSTETRIC  MEDICINE  AND  SURGERY.  In  one 
imperial  octavo  volume  of  640  pages,  with  64  plates  and  numerous 
engravings  in  the  text.  Strongly  bound  in  leather,  $7. 

REICHERT  (EDWARD  T.).    A  TEXT-BOOK  ON  PHYSIOLOGY. 

In  one  handsome  octavo  volume  of  about  800  pages,  richly  illustrated. 
Preparing. 

REMSEN  (IRA).  THE  PRINCIPLES  OF  THEORETICAL  CHEM- 
ISTRY. New  (5th)  edition,  thoroughly  revised.  In  one  12mo.  vol- 
ume of  326  pages.  Cloth,  $2. 


A  clear  and  concise  explanation 
of  a  difficult  subject.  We  cordially 
recommend  it. — The  London  Lancet. 

The  book  is  equally  adapted  to  the 
student  of  chemistry  or  the  practi- 
tioner who  desires  to  broaden  his 
theoretical  knowledge  of  chemistry. 
— New  Orleans  Med.  and  Surg.  Jour. 

The  appearance  of  a  fifth  edition 
of  this  treatise  is  in  itself  a  guarantee 


that  the  work  has  met  with  general 
favor.  This  is  further  established 
by  the  fact  that  it  has  been  trans- 
lated into  German  and  Italian.  The 
treatise  is  especially  adapted  to  the 
laboratory  student.  It  ranks  unusu- 
ally high  among  the  works  of  this 
class.  This  edition  has  been  brought 
fully  up  to  the  times. — American 
Medico- Surgical  Bulletin. 


RICHARDSON  (BENJAMIN  WARD).  PREVENTIVE  MEDI- 
CINE. In  one  octavo  volume  of  729  pages.  Cloth,  $4 ;  leather,  $5. 

ROBERTS  (JOHN  B.).  THE  PRINCIPLES  AND  PRACTICE  OF 
MODERN  SURGERY.  New  (2d)  edition.  In  one  octavo  volume  of 
about  800  pages,  with  about  500  engravings.  Shortly. 

THE  COMPEND  OF  ANATOMY.     For  use  in  the  Dissecting 

Room  and  in  preparing  for  Examinations.     In  one  16mo.  volume  of 
196  pages.    Limp  cloth,  75  cents. 

ROBERTS  (SIR  WILLIAM).  A  PRACTICAL  TREATISE  ON 
URINARY  AND  RENAL  DISEASES,  INCLUDING  URINARY 
DEPOSITS.  Fourth  American  from  the  fourth  London  edition.  In 
one  very  handsome  8vo.  vol.  of  609  pp.,  with  81  illus.  Cloth,  $3.50. 

ROBERTSON  (J.  MCGREGOR).  PHYSIOLOGICAL  PHYSICS. 
In  one  12mo.  volume  of  537  pages,  with  219  engravings.  Cloth,  $2. 
See  Student's  Series  of  Manuals,  page  27. 

ROSS  (JAMES).  A  HANDBOOK  OF  THE  DISEASES  OF  THE 
NERVOUS  SYSTEM.  In  one  handsome  octavo  volume  of  726  pages, 
with  184  engravings.  Cloth,  $4.50 ;  leather,  $5.50. 

SAVAGE  (GEORGE  H.).  INSANITY  AND  ALLIED  NEUROSES, 
PRACTICAL  AND  CLINICAL.  In  one  12mo.  volume  of  551  pages, 
with  18_  typical  engravings.  Cloth,  $2.  See  Series  of  Clinical  Man- 
ualt,  page  25. 


LEA  BBOTHEES  &  Co.,  PHILADELPHIA  AND  NEW  YOEK.     25 

SCHAFER   (EDWARD  A.).     THE  ESSENTIALS  OF  HISTOL- 
OGY. DESCRIPTIVE  AND  PRACTICAL.  For  the  use  of  Students. 
New  (5th)  edition.    In  one  handsome  octavo  volume  of  359  pages, 
with  392  illustrations.     Cloth,  $3.00,  net.    Just  ready. 
Nowhere  else  will  the  same  very  I      The  most  satisfactory  elementary 

moderate  outlay  secure  as  thoroughly    text-book  of  histology  in  the   Eng- 

useful  and  interesting   an    atlas  of  j  lish  language. — The  Boston  Med.  and 

structural  anatomy. — The  American    Sur.  Jour. 

Journal  of  the  Medical  Sciences. 

A  COURSE  OF  PRACTICAL  HISTOLOGY.    New  (2d)  edition. 

In  one  12mo.  volume  of  307  pages,  with  59  engravings.   Cloth,  $2.25. 


The  book  very  nearly  approaches 
perfection.  Methods  are  given  with 
an  accuracy  of  detail  and  prevision 
of  difficulties  which  can  hardly  be 


overpraised.  It  bears  eloquent  tes- 
timony to  the  wide  knowledge  and 
untiring  industry  of  its  author. — 
The  Scottish  Med.  and  Surg.  Jour. 


SCHLEIF  (WILLIAM).  MATERIA  MEDICA,  THERAPEUTICS, 
PRESCRIPTION  WRITING,  MEDICAL  LATIN,  ETC.  12mo., 
352  pages.  Cloth,  $1.50,  net.  Just  ready.  Lea's  Series  of  Pocket 
Text-books.  Edited  by  BERN  B.  GALLAUDET,  M.  D.  See  page  18. 

SCHMTTZ  AND  ZUMPT'S  CLASSICAL  SERIES.  Advanced 
Latin  Exercises.  Cloth,  60  cts.  Schmidt's  Elementary  Latin  Exer- 
cises. Cloth,  50  cents.  Sallust.  Cloth,  60  cents.  Nepos.  Cloth,  60 
cents.  Virgil.  Cloth,  85  cents.  Curtius.  Cloth,  80  cents. 

SCHOFEELD    (ALFRED    T.).      ELEMENTARY    PHYSIOLOGY 

FOR  STUDENTS.        In  one  12mo.  volume  of  380  pages,  with  227 
engravings  and  2  colored  plates.    Cloth,  $2. 

SCHREIBER  (JOSEPH).  A  MANUAL  OF  TREATMENT  BY 
MASSAGE  AND  METHODICAL  MUSCLE  EXERCISE.  Octavo 
volume  of  274  pages,  with  117  engravings. 

SENN  (NICHOLAS).  SURGICAL  BACTERIOLOGY.  Second  edi- 
tion. In  one  octavo  volume  of  268  pages,  with  13  plates,  10  of  which 
are  colored,  and  9"  engravings.  Cloth,  §2. 

SERIES  OF  CLINICAL  MANUALS.  A  Series  of  Authoritative 
Monographs  on  Important  Clinical  Subjects,  in  12mo.  volumes  of  about 
550  pages,  well  illustrated.  The  following  volumes  are  now  ready : 
YEO  on  Food  in  Health  and  Disease,  new  (2d)  edition,  $2.50;  CARTER 
and  FROST'S  Ophthalmic  Surgery,  $2.25 ;  HUTCHINSON  on  Syphilis, 
$2.25;  MARSH  on  Diseases  of  the  Joints,  $2;  OWEN  on  SurgicalDis- 
eases  of  Children,  $2;  PICK  on  Fractures  and  Dislocations,  $2;  SAVAGE 
on  Insanity  and  Allied  Neuroses,  $2. 
For  separate' notices,  see  under  various  authors'  names. 

SERIES  OF  STUDENT'S  MANUALS.    See  page  27. 

SIMON  (CHARLES  E.).  CLINICAL  DIAGNOSIS,  BY  MICRO- 
SCOPICAL AND  CHEMICAL  METHODS.  New  (2d)  edition.  In 
one  very  handsome  octavo  volume  of  530  pages,  with  135  engravings 
and  14  full-page  colored  plates.  Cloth,  $3.50.  Just  ready. 

This  book  thoroughly  deserves  its  j  In  all  respects  entirely  up  to  date, 
success.  It  is  a  very  complete,  authen- 1  — Medical  Record. 
tic  and  useful  manual  of  the  micro- ;  The  chapter  on  examination  of 
scopical  and  chemical  methods  j  the  urine  is  the  most  complete  and 
which  are  employed  in  diagnosis,  j  advanced  that  we  know  of  in  the 
Very  excellent  colored  plates  illus-  i  English  language. — Canadian  Prac- 


trate  this  work.—  New  York  Medical 
Journal. 


titioner. 


26     LEA  BROTHERS  &  Co.,  PHILADELPHIA  AND  NEW  YORK. 


SIMON  (W.).  MANUAL  OF  CHEMISTRY.  A  Guide  to  Lectures 
and  Laboratory  Work  for  Beginners  in  Chemistry.  A  Text-book 
specially  adapted  for  Students  of  Pharmacy  and  Medicine.  New  (6th) 
edition.  In  one  8vo.  volume  of  536  pages,  with  46  engravings  and  8 
plates  showing  colors  of  64  tests.  Cloth,  $3.00,  net.  Just  ready. 

It  is  difficult  to  see  how  a  better  i  the  covers  of  this  book. — The  North- 
book  could  be  constructed.     No  man    western  Lancet. 
who  devotes  himself  to  the  practice       Its  statements  are  all  clear  and  its 
of  medicine  need  know  more  about  j  teachings    are  practical. —  Virginia 
chemistry  than  is  contained  between  |  Med.  Monthly. 

SLADE  (D.  D.).  DIPHTHERIA;  ITS  NATURE  AND  TREAT- 
MENT. Second  edition.  In  one  royal  12mo.  vol.,  158  pp.  Cloth,  $1.25. 

SMITH  (EDWARD).  CONSUMPTION;  ITS  EARLY  AND  REME- 
DIABLE STAGES.  In  one  8vo.  volume  of  253  pp.  Cloth,  $2.25. 

SMITH  (J.  LEWIS).  A  TREATISE  ON  THE  DISEASES  OF  IN- 
FANCY AND  CHILDHOOD.  Eighth  edition,  thoroughly  revised 
and  rewritten  and  much  enlarged.  In  one  large  8vo.  volume  of  983 
pages,  with  273  engravings  and  4  full-page  plates.  Cloth,  $4.50; 
leather,  $5.50. 
The  most  complete  and  satisfac-  j  can  more  than  hold  its  own  against 

i j.1 i_  *j-|_i«i  ,1  t.  ,•  rt,i° 


tory  text-book  with  which  we  are 
acquainted. — American  Gynecologi- 
cal and  Obstetrical  Journal. 

It  truly  is  the  most  evenly  bal- 
anced, clear  in  description  and 
thorough  in  detail  of  any  of  the 
books  published  in  this  country  on 


any  other  work  treating  of  the  same 
subj  ect. — A  merican  Medico- Surgica  I 
Bulletin. 

A  safe  guide  for  students  and  phy- 
sicians.— The  Am.  Jour,  of  Obstetrics. 

For  years  the  leading  text-book  on 
children's  diseases  in  America. — 


this  subject.— Medical  Fortnightly.  \  Chicago  Medical  Recorder. 
A  treatise  which  in  every  respect  I 

SMITH  (STEPHEN).  OPERATIVE  SURGERY.  Second  and  thor- 
oughly revised  edition.  In  one  octavo  volume  of  892  pages,  with 
1005  engravings.  Cloth,  $4  ;  leather,  $5. 


One  of  the  most  satisfactory  works 
on  modern  operative  surgery  yet 
published.  The  book  is  a  compen- 


dium for  the  modern  surgeon. — Bos- 
ton Medical  and  Surgical  Journal. 


SOLLY  (S.  EDWIN).  A  HANDBOOK  OF  MEDICAL  CLIMA- 
TOLOGY. In  one  handsome  octavo  volume  of  462  pages,  with  en- 
gravings and  11  full-page  plates,  5  of  which  are  in  colors.  Cloth,  $4.00. 
Just  ready. 


A  clear  and  lucid  summary  of 
what  is  known  of  climate  in  relation 
to  its  influence  upon  human  beings. 
— The  Therapeutic  Gazette. 

The  book  is  admirably  planned, 
clearly  written, and  the  author  speaks 
from  an  experience  of  thirty  years  as 


an  accurate  observer  and  practical 
therapeutist. — Maryland  Med.  Jour. 
Every  practitioner  of  medicine 
should  possess  himself  of  a  copy  and 
study  it,  and  we  are  sure  he  will 
never  regret  it. — St.  Louis  Medical 
and  Surgical  Journal. 


STILLE  (ALFRED).  CHOLERA;  ITS  ORIGIN,  HISTORY,  CAUS- 
ATION, SYMPTOMS,  LESIONS,  PREVENTION  AND  TREAT- 
MENT. In  one  12mo.  volume  of  163  pages,  with  a  chart  showing 
routes  of  previous  epidemics.  Cloth,  $1.25. 

THERAPEUTICS   AND    MATERIA    MEDICA.      Fourth    and 

revised  edition.      In  two  octavo  volumes,  containing    1936    pages. 
Cloth,  $10;  leather,  $12. 


LEA  BROTHERS  &  Co.,  PHILADELPHIA  AND  NEW  YOEK.     27 

STELLE  (ALFRED),  MAISCH  (JOHN  M.)  AND  CASPABI 
(CHAS.  JR.).  THE  NATIONAL  DISPENSATORY:  Containing 
the  Natural  History,  Chemistry,  Pharmacy,  Actions  and  Uses  of 
Medicines,  including  those  recognized  in  the  latest  Pharmacopoeias  of 
the  United  States,  Great  Britain  and  Germany,  with  numerous  refer- 
ences to  the  French  Codex.  Fifth  edition,  revised  and  enlarged, 
including  the  new  U.  S.  Pharmacopoeia,  Seventh  Decennial  Revision. 
With  Supplement  containing  the  new  edition  of  the  National  Formu- 
lary. In  one  magnificent  imperial  octavo  volume  of  about  2025  pages, 
with  320  engravings.  Cloth,  $7.25;  leather,  $8.  With  ready  reference 
Thumb-letter  Index.  Cloth,  $7.75  ;  leather,  $8.50. 
Recommended  most  highly  for  the  amount  of  information  contained  in 


physician,  and  invaluable  to  the 
druggist. — Therapeutic  Gazette. 

It,  is  the  official  guide  for  the  Med- 
ical and  Pharmaceutical  professions. 
— Buffalo  Med.  and  Sur.  Jour. 

The  readiness  with  which  the  vast 


this  work  is  made  available  is  indi- 
cated by  the  twenty-five  thousand 
references  in  the  two  indexes. — Bos- 
ton Medical  and  Surgical  Journal. 
Should  be  recognized  as  a  national 
standard. — North  Am.  Practitioner. 


STIMSON  (LEWIS  A.).    A  MANUAL  OF  OPERATIVE  SURGERY. 

New  (3d)  edition.     In  one  royal  12mo.  volume  of  614  pages,  with  306 
engravings.     Cloth,  $3.75. 


A  useful  and  practical  guide  for 
all  students  and  practitioners. — Am. 
Journal  of  the  Medical  Sciences. 


The  book  is  worth  the  price  for  the 
illustrations  alone. — Ohio  Medical 
Journal. 


STIMSON  (LEWIS  A.).     A  TREATISE  ON  FRACTURES    AND 

DISLOCATIONS.  In  one  handsome  octavo  volume    of  831  pages, 

with  326  engravings  and  20  plates.     Just  ready.    Cloth,  $5.00,  net  ; 

leather,  $6.00,  net. 

Preeminently   the    authoritative  I      Taken  as  a  whole,  the  work  is  the 

text-book  upon  the   subject.      The    best  one    in    English     to-day. — St. 

vast  experience  of  the  author  gives    Louis  Medical  and  Surgical  Journal. 

to  his  conclusions  an  unimpeachable        Pointed,  practical,  comprehensiv  e, 

value.     The  work  is  profusely  il-    exhaustive,  authoritative,  well  writ- 

lustrated.    It  will  be   found  indis- ;  ten    and    well    arranged. — Denver 

pensable  to  the  student  and  the  prac-    Medical  Times. 

titioner  alike. —  The  Medical  Age.    \ 

STUDENT'S  QUIZ  SERIES.  Thirteen  volumes,  convenient,  author- 
itative, well  illustrated,  handsomely  bound  in  cloth.  1.  Anatomy 
(double  number);  2.  Physiology;  3.  Chemistry  and  Physics ;  4.  Histol- 
ogy, Pathology,  and  Bacteriology;  5.  Materia  Medica  and  Thera- 
peutics ;  6.  Practice  of  Medicine ;  7.  Surgery  (double  number);  8.  Genito- 
Urinary  and  Venereal  Diseases ;  9.  Diseases  of  the  Skin;  10.  Diseases 
of  the  Eye,  Ear,  Throat  and  Nose;  11.  Obstetrics ;  12.  Gynecology; 
13.  Diseases  of  Children.  Price,  $1  each,  except  Nos.  1  and  7, 
Anatomy  and  Surgery,  which  being  double  numbers  are  priced  at 
$1.75  each.  Full  specimen  circular  on  application  to  publishers. 

STUDENT'S  SERIES  OF  MANUALS.  12mos.  of  from  300-540 
pages,  profusely  illustrated,  and  bound  in  red  limp  cloth.  HERMAN'S 
First  Lines  in  Midwifery,  $1.25 ;  LUFF'S  Manual  of  Chemistry,  $2  ; 
BRUCE'S  Materia  Medica  and  Therapeutics  (sixth  edition),  $1.50.  net. 
BELL'S  Comparative  Anatomy  and  Physiology,  $2;  ROBERT- 
SON'S Physiological  Physics,  $2;  GOULD'S  Surgical  Diagnosis,  $2; 
KLEIN'S  Elements  of  Histology  (5th  edition),  $2.00,  net ;  PEPPER'S 
Surgical  Pathology,  $2;  TREVES'  Surgical  Applied  Anatomy,  $2; 
RALFE'S  Clinical  Chemistry,  $1.50;  and  CLARKE  and  LOCKWOOD'S 
Dissector's  Manual,  $1.50.  The  following  is  in  press :  PEPPER'S 
Forensic  Medicine. 
For  separate  notices,  see  under  various  author's  names. 


28     LEA  BBOTHEKS  A  Co.,  PHILADELPHIA  AND  NEW  YOBK. 


STURGES  (OCTAVIUS).  AN  INTRODUCTION  TO  THE  STUDY 
OF  CLINICAL  MEDICINE.  In  one  12mo.  volume.  Cloth,  $1.25. 

SUTTON  (JOHN  BLAND).  SURGICAL  DISEASES  OF  THE 
OVARIES  AND  FALLOPIAN  TUBES.  Including  Abdominal 
Pregnancy.  In  one  12mo.  volume  of  513  pages,  with  119  engravings 
and  5  colored  plates.  Cloth,  $3. 

TAIT  (LAWSON).  DISEASES  OF  WOMEN  AND  ABDOMINAL 
SURGERY.  In  two  handsome  octavo  volumes.  Vol.  I.  contains  546 
pages  and  3  plates.  Cloth,  $3. 


TANNER  (THOMAS  HAWKES)  ON  THE  SIGNS  AND  DIS- 
EASES OF  PREGNANCY.  From  the  second  English  edition.  In 
one  octavo  volume  of  490  pages,  with  4  colored  plates  and  16  engrav- 
ings. Cloth,  $4.25. 

TAYLOR  (ALFRED  S.).  MEDICAL  JURISPRUDENCE.  New 
American  from  the  twelfth  English  edition,  specially  revised  by  CLARK 
BELL,  ESQ.,  of  the  N.  Y.  Bar.  In  one  8vo.  vol.  of  831  pages,  with  54 
engrs.  and  8  full-page  plates.  Cloth,  $4.50;  leather,  $5.50  Just  ready. 


To  the  student,  as  to  the  physician, 
we  would  say,  get  Taylor  first,  and 
then  add  as  means  and  inclination 
enable  you. — American  Practitioner 
and  News. 

It  is  the  authority  accepted  as 
final  by  the  courts  of  all  English- 
speaking  countries.  This  is  the  im- 
portant consideration  for  medical 
men,  since  in  the  event  of  their 
being  summoned  as  experts  or  wit- 


nesses, it  strongly  behooves  them  to 
be  prepared  according  to  the  princi- 
ples and  practice  everywhere  ac- 
cepted. The  work  will  be  found  to 
be  thorough,  authoritative  and 
modern. — Albany  Law  Journal. 

Probably  the  best  work  on  the 
subject  written  in  the  English  lan- 
guage. The  work  has  been  thor- 
oughly revised  and  is  up  to  date. — 
Pacific  Medical  Journal. 


—  ON  POISONS  IN  RELATION  TO  MEDICINE  AND  MEDI- 
CAL JURISPRUDENCE.  Third  American  from  the  third  London 
edition.  In  one  octavo  volume  of  788  pages,  with  104  illustrations. 
Cloth,  $5.50;  leather,  $6.50. 


TAYLOR  (ROBERT  W.).     THE    PATHOLOGY  AND   TREAT- 
MENT OF  VENEREAL  DISEASES.    New  (2d)  edition.    In  one 
very  handsome  octavo  volume  of  about  700  pages,  with  about  200  en- 
gravings and  6  colored  plates.    In  press. 
Notices  of  previous  edition  are  appended. 


By  long  odds  the  best  work  on 
venereal  diseases. — Louisville  Medi- 
cal Monthly. 

In  the  observation  and  treatment 
of  venereal  diseases  his  experience 
has  been  greater  probably  than  that 
of  any  other  practitioner  of  this  con- 
tinent.— New  York  Medical  Journal. 

The  clearest,  most  unbiased  and 
ably  presented  treatise  as  yet  pub- 
lished on  this  vast  subject. — The 
Medical  News. 

Decidedly  the  most  important  and 
authoritative  treatise  oa  venereal 


diseases  that  has  in  recent  years  ap- 
peared in  English. — American  Jour- 
nal of  the  Medical  Sciences. 

It  is  a  veritable  storehouse  of  our 
knowledge  of  the  venereal  diseases. 
It  is  commended  as  a  conservative, 
practical,  full  exposition  of  the 
greatest  value. — Chicago  Clinical 
Review. 

The  best  work  on  venereal  dis- 
eases in  the  English  language.  It 
is  certainly  above  everything  of  the 
kind. — The  St.  Louis  Medical  and 
Surgical  Journal. 


LEA  BROTHERS  &  Co.,  PHILADELPHIA  AND  NEW  YORK.     29 

TAYL.OR  (ROBERT  W.).  A  PRACTICAL  TREATISE  ON  SEX- 
UAL DISORDERS  IN  THE  MALE  AND  FEMALE.  In  one 
8vo.  vol.  of  448  pp.,  with  73  engravings  and  8  colored  plates.  Cloth, 
$3.  Net. 


It  is  a  timely,  boon  to  the  medical 
profession  that  an  observer  of  Dr. 
Taylor's  skill  and  experience  has 
written  a  work  on  this  hitherto 
neglected  and  little  understood  class 
of  diseases  which  places  them  on  a 
scientific  basis  and  renders  them  so 
clear  that  the  physician  who  reads 


the  female  is  presented  in  an  exhaus- 
tive manner,  all  of  the  causes  pro- 
ducing it  being  described.  The 
author  has  presented  to  the  profes- 
sion the  ablest  and  most  scientific 
work  as  yet  published  on  sexual 
disorders,  and  one  which,  if  carefully 
followed,  will  be  of  unlimited  value 


its    pages    can   treat  this    class  of  i  to   both   physician    and  patient. — 
patients  intelligently.     Sterility  in  I  Medical  News. 

A  CLINICAL  ATLAS  OF  VENEREAL  AND  SKIN  DISEASES. 

Including  Diagnosis,  Prognosis  and  Treatment.  In  eight  large  folio 
parts,  measuring  14  x  18  inches,  and  comprising  213  beautiful  figures 
on  58  full-page  chromo-lithographic  plates,  85  fine  engravings  and  425 
pages  of  text.  Complete  work  now  ready.  Price  per  part,  sewed  in 
heavy  embossed  paper,  $2.50.  Bound  in  one  volume,  half  Russia, 
$27 ;  half  Turkey  Morocco,  $28.  For  sale  by  subscription  only.  Address 
the  publishers.  Specimen  plates  by  mail  on  receipt  of  ten  cents. 

TAYLOR  (SEYMOUR).  INDEX  OF  MEDICINE.  A  Manual  for 
the  use  of  Senior  Students  and  others.  In  one  large  12mo.  volume  of 
802  pages.  Cloth,  $3.75. 

THOMAS  (T.  GAELL.ARD)  AND  MUNDE  (PAUL  P.).  A  PRAC 
TICAL  TREATISE  ON  THE  DISEASES  OF  WOMEN.  Sixth 
edition,  thoroughly  revised  by  PAUL  F.  MUNDE,  M.  D.  In  one 
large  and  handsome  octavo  volume  of  824  pages,  with  347  engravings. 
Cloth,  $5 ;  leather,  $6. 


The  best  practical  treatise  on  the 
subject  in  the  English  language. 
It  will  be  of  especial  value  to  the 
general  practitioner  as  well  as  to  the 
specialist.  The  illustrations  are  very 


This  work,  which  has  already  gone 
through  five  large  editions,  and  has 
been  translated  into  French,  Ger- 
man, Spanish  and  Italian,  is  the 
most  practical  and  at  the  same  time 


satisfactory.  Many  of  them  are  new  |  the  most  complete  treatise  upon  the 
and  are  particularly  clear  and  attrac- j  subject. — The  Archives  of  Gynecol- 
tive. — Boston  Med .  and  Sur.  Jour.  '  ogy,  Obstetrics  and  Pediatrics. 

THOMPSON  (SIR  HENRY).  CLINICAL  LECTURES  ON  DIS- 
EASES OF  THE  URINARY  ORGANS.  Second  and  revised  edi- 
tion. In  one  octavo  vol.  of  203  pp.,  with  25  engravings.  Cloth,  $2.25. 

THE    PATHOLOGY   AND  TREATMENT  OF   STRICTURE 

OF  THE  URETHRA  AND  URINARY  FISTULA.  From  the 
third  English  edition.  In  one  octavo  volume  of  359  pages,  with  47 
engravings  and  3  lithographic  plates.  Cloth,  $3.50. 

THOMSON  (JOHN).  DISEASES  OF  CHILDREN.  In  one  crown 
octavo  volume  of  350  pages,  with  52  illus.  Cloth,  $1.75,  net.  Just  ready. 

TODD  (ROBERT  BENTL.EY).  CLINICAL  LECTURES  ON  CER- 
TAIN ACUTE  DISEASES.  In  one  8vo.  vol.  of  320  pp.,  cloth,  $2.50. 

TREVES  (FREDERICK).  OPERATIVE  SURGERY.  In  two 
8vo.  vols.  containing  1550  pp.,  with  422  illus.  Cloth,  $9 ;  leath.,  $11. 

A  SYSTEM  OF  SURGERY.  In  Contributions  by  Twenty-five 

English  Surgeons.  In  two  large  octavo  volumes.  Vol.  I.,  1178  pages, 
with  463  engravings  and  2  colored  plates.  Vol.  II.,  1120  pages,  with 
487  engravings  and  2  colored  plates.  Complete  work,  cloth,  $16.00. 


30     LEA  BBOTHEES  &  Co.,  PHILADELPHIA  AND  NEW  YOEK. 

TREVES  (FREDERICK).  SURGICAL  APPLIED  ANATOMY.  In 
one  12mo.  volume  of  540  pages,  with  61  engravings.  Cloth,  $2.  See 
Student's  Series  of  Manuals,  page  27. 

TUTTL.E  (GEORGE  M.).  A  POCKET  TEXT-BOOK  OF  DISEASES 
OF  CHILDREN".  In  one  handsome  12mo.  volume  of  about  300  pages, 
with  many  illustrations.  Cloth,  $1.50,  net.  Shortly.  Lea's  Series  of 
Pocket  Text-looks,  edited  by  BERN  B.  GALLATTDET,  M.  D.  See  p  18. 

VAUGHAN    (VICTOR    C.)    AND    NOVY    (FREDERICK    G.). 

PTOMAINS,  LEUCOMAINS,  TOXINS  AND  ANTITOXINS, 
or  the  Chemical  Factors  in  the  Causation  of  Disease.  New  (3d)  edition. 
In  one  12mo.  volume  of  603  pages.  Cloth,  $3. 


The  work  has  been  brought  down 
to  date,  and  will  be  found  entirely 
satisfactory. — Journal  of  the  Ameri- 
can Medical  Association. 

The  most  exhaustive  and  most  re- 
cent presentation  of  the  subject. — 
American  Jour,  of  the  Med.  Sciences. 


The  present  edition  has  been  not, 
only  thoroughly  revised  throughout 
but  also  greatly  enlarged,  ample 
consideration  being  given  to  the  new 
subjects  of  toxins  and  antitoxins. — 
Tri-State  Medical  Journal. 


VISITING  L.IST.  THE  MEDICAL  NEWS  VISITING  LIST  for  1899. 
Four  styles :  Weekly  (dated  for  30  patients);  Monthly  (undated  for 
120  patients  per  month);  Perpetual  (undated  for  30  patients  each 
week);  and  Perpetual  (undated  for  60  patients  each  week).  The  60- 
patient  book  consists  of  256  pages  of  assorted  blanks.  The  first  three 
styles  contain  32  pages  of  important  data,  thoroughly  revised,  and 
160  pages  of  assorted  blanks.  Each  in  one  volume,  price,  $1.25. 
With  thumb-letter  index  for  quick  use,  25  cents  extra.  Special  rates 
to  advance-paying  subscribers  to  THE  MEDICAL  NEWS  or  THE 
AMERICAN  JOURNAL  OF  THE  MEDICAL  SCIENCES,  or  both.  See  p.  32. 

WATSON  (THOMAS).  LECTURES  ON  THE  PRINCIPLES  AND 
PRACTICE  OF  PHYSIC.  A  new  American  from  the  fifth  and 
enlarged  English  edition,  with  additions  by  H.  HARTSHORNE,  M.  D . 
In  two  large  8vo.  vols.  of  1840  pp.,  with  190  cuts.  Cloth,  $9 ;  leather,  $1 1 . 

WEST  (CHARLES).  LECTURES  ON  THE  DISEASES  PECULIAR 
TO  WOMEN.  Third  American  from  the  third  English  edition.  In 
one  octavo  volume  of  543  pages.  Cloth,  $3.75 ;  leather,  $4.75. 

ON  SOME  DISORDERS  OF  THE   NERVOUS  SYSTEM  IN 


CHILDHOOD.    In  one  small  12mo.  volume  of  127  pages.    Cloth,  $1. 

WHARTON  (HENRY  R.).    MINOR  SURGERY  AND  BANDAG- 
ING.   New  (4th)  edition.    In  one  12mo.  vol.  of  about  600  pages,  with 
about  500  engravings,  many  of  which  are  photographic.    Shortly. 
Notices  of  previous  edition  are  appended. 


We  know  of  no  book  which  more 
thoroughly  or  more  satisfactorily 
covers  the  ground  of  Minor  Surgery 
and  Bandaging. — Brooklyn  Medical 
Journal. 

Well  written,  conveniently  ar- 
ranged and  amply  illustrated.  It 
covers  the  field  so  fully  as  to  render 
it  a  valuable  text-book,  as  well  as  a 


work  of  ready  reference  for  sur- 
geons.— North  Amer.  Practitioner. 
The  part  devoted  to  bandaging  is 
perhaps  the  best  exposition  of  the 
subject  in  the  English  language.  It 
can  be  highly  commended  to  the 
student,  the  practitioner  and  the 
specialist. — The  Chicago  Medical 
Recorder. 


LEA  BEOTHEBS  &  Co.,  PHILADELPHIA  AND  NEW  YORK.     31 

WHITLA  (WILLIAM).  DICTIONARY  OF  TREATMENT,  OR 
THERAPEUTIC  INDEX.  Including  Medical  and  Surgical  Thera- 
peutics. In  one  square  octavo  volume  of  917  pages.  Cloth,  $4. 

WILLIAMS  (DAWSON).  THE  MEDICAL  DISEASES  OF  CHIL- 
DREN. In  one  12mo.  volume  of  629  pages,  with  18  illustrations. 
Just  ready.  Cloth,  $2.50,  net. 

The  descriptions  of  symptoms  are  j  diagnoses,  prognosis,  complications, 
full,  and  the  treatment  recommended  j  and  treatment.  The  work  is  up  to 
will  meet  general  approval.  Under  !  date  in  every  sense. — The  Charlotte 
each  disease  are  given  the  symptoms,  Medical  Journal. 

WILSON  (ERASMUS).    A    SYSTEM    OF    HUMAN    ANATOMY. 

A  new  and  revised  American  from  the  last  English  edition.  Illustrated 
with  397  engravings.  In  one  octavo  volume  of  616  pages.  Cloth,  $4 ; 
leather,  $5. 

THE  STUDENT'S  BOOK  OF  CUTANEOUS  MEDICINE.    In 

one  12mo.  volume.    Cloth,  $3.50. 

WINCKEL  ON  PATHOLOGY  AND  TREATMENT  OF  CHILDBED. 
Translated  by  JAMES  R.  CHADWICK,  A.  M.,  M.  D.  With  additions 
by  the  Author.  In  one  octavo  volume  of  484  pages.  Cloth,  $4. 

WOHLER'S  OUTLINES  OF  ORGANIC  CHEMISTRY.  Translated 
from  the  eighth  German  edition,  by  IRA  REMSEN,  M.  D.  In  one 
12mo.  volume  of  550  pages.  Cloth,  $3. 

YEAR-BOOK  OF  TREATMENT  FOR  1892,  1893,  1896,1897  and  1898. 
Critical  Reviews  for  Practitioners  of  Medicine  and  Surgery.  In  con- 
tributions by  25  well-known  medical  writers.  12mos.,  about  500  pages 
each.  Cloth,  $1.50.  In  combination  with  THE  MEDICAL  NEWS  and 
THE  AMERICAN  JOURNAL  OF  THE  MEDICAL  SCIENCES,  75  cents. 

YEO  (I.  BURNEY).  FOOD  IN  HEALTH  AND  DISEASE.  New 
(2d)  edition.  In  one  12mo.  volume  of  592  pages,  with  4  engravings. 
Cloth,  $2.50.  See  Series  of  Clinical  Manuals,  page  26. 

We  doubt  whether  any  book  on  |  work  of  Dr.  Yeo's.    The  value  of 


dietetics  has  been  of  greater  or  more 
widespread  usefulness  than  has  this 
much-quoted  and  much-consulted 


the  work  is  not  to  be  overestimated. 
— New  York  Medical  Journal. 


A  MANUAL  OF   MEDICAL  TREATMENT,  OR  CLINICAL 

THERAPEUTICS.  Two  volumes  containing  1275  pages.  Cloth,  $5.50. 

YOUNG  (JAMES  K.).    ORTHOPEDIC  SURGERY.    In   one    8vo. 
volume  of  475  pages,  with  286  illustrations.     Cloth,  $4 ;  leather,  $5. 

In  studying  the  different  chapters,  surgical  specialty  and  every  page 

one  is  impressed  with  the  thorough-  abounds   with    evidences    of  prac- 

ness  of  the  work.    The  illustrations  ticality.     It  is  the  clearest  and  most 

are  numerous — the  book  thoroughly  modern  work  upon  this  growing  de- 

practical — Medical  News.  partment  of  surgery. — The  Chicago 

It  is  a  thorough,  a  very  cpmpre-  Clinical  Review. 
fcensive  work  upon  this  legitimate 


PERIODICALS. 


PROGRESSIVE  MEDICINE. 

A  Quarterly  Digest  of  New  Methods,  Discoveries,  and  Improvements 
in  the  Medical  and  Surgical  Sciences  by  Eminent  Authorities.  Edited  by 
Dr.  Hobart  Amory  Hare.  In  four  abundantly  illustrated,  cloth  bound, 
octavo  volumes,  of  400-500  pages  each,  issued  quarterly,  commencing 
March  1st,  1899.  Per  annum  (4  volumes),  $10.00  delivered. 


THE  MEDICAL  NEWS. 

"Weekly,  $i.OO  per  Annum. 

Each  number  contains  32  quarto  pages,  abundantly  illustrated, 
crisp,  fresh  weekly  professional  newspaper. 


THE  AMERICAN  JOURNAL  OF  THE  MEDICAL  SCIENCES. 

Monthly,  #  J.OO  Per  Annum. 

Each  issue  contains  128  octavo  pages,  fully  illustrated.    The  most 
advanced  and  enterprising  American  exponent  of  scientific  medicine. 


THE  MEDICAL   NEWS   VISITING   LIST. 

Four  styles,  Weekly  (dated  for  30  patients) ;  Monthly  (undated,  for 
120  patients  per  month);  Perpetual  (undated,  for  30  patients  weekly  per 
year) ;  and  Perpetual  (undated,  for  60  patients  per  year).  Each  style  in 
one  wallet-shaped  book,  leather  bound,  with  pocket,  pencil  and  rubber. 
Price,  each,  $1.2i.  Thumb-letter  index,  25  cents  extra. 


THE  MEDICAL  NEWS   POCKET  FORMULARY. 

Containing  1600  prescriptions  representing  the  latest  and  most  ap- 
proved methods  of  administering  remedial  agents.  Strongly  bound  in 
leather ;  with  pocket  and  pencil.  Price,  $1.50,  net. 


COMBINATION    RATES: 

.     American  Journal  of  the  Alone.  In  Combination. 

Medical  Sciences $   4.OO  ^    Ai7KAl 

I     Medical  News 4.OO  }   $7'50  I  $15.00 

<     Progressive  Medicine  ....      10.0O  j 

g     Medical  News  Visiting  List         .        .        .        1.35 

°-     Medical  News  Formulary  .        .        .         1.50  net, 

In  all  #20.75  for  #1(3. OO 

First  four  above  publications  in  combination        .        .        !$15.75 
All  above  publications  in  combination    ....          16.00 

Other  Combinations  will  be  quoted  on  request. 
Full  Circulars  and  Specimens  free. 


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706,  708  &  710  Sansom  St.,  Philadelphia. 
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